public DataTemplate CellTemplate { get; set; }

Public Property CellTemplate As DataTemplate

<dx:ThemedWindow
    x:Class="HowToEditCell.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
    xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors"
    xmlns:dxpg="http://schemas.devexpress.com/winfx/2008/xaml/pivotgrid"
    xmlns:local="clr-namespace:HowToEditCell"
    Width="800"
    Height="450"
    Loaded="Window_Loaded"
    Title="How to Edit Cell">

    <Grid>
        <dxpg:PivotGridControl
            x:Name="pivotGridControl1"
            local:PivotGridEditHelper.OnCellEdit="pivotGridControl1_OnCellEdit"
            local:PivotGridEditHelper.UseHelper="{Binding RelativeSource={RelativeSource Self}}">
            <dxpg:PivotGridControl.Fields>
                <dxpg:PivotGridField
                    x:Name="fieldSales"
                    Area="DataArea"
                    Caption="Product Sales"
                    FieldName="ExtendedPrice">
                    <dxpg:PivotGridField.CellTemplate>
                        <DataTemplate>
                            <dxe:TextEdit
                                x:Name="edit"
                                HorizontalContentAlignment="Right"
                                DisplayFormatString="c2"
                                EditMode="InplaceInactive"
                                EditValue="{Binding Value, Mode=OneWay}"
                                local:PivotGridEditHelper.LostFocusCommand="{x:Static local:PivotGridEditHelper.Enter}"
                                Mask="[0-9]*\.[0-9]{0,2}"
                                MaskType="RegEx">
                                <dxe:TextEdit.InputBindings>
                                    <KeyBinding
                                        Key="Enter"
                                        Command="{x:Static local:PivotGridEditHelper.Enter}"
                                        CommandParameter="{Binding ElementName=edit}" />
                                    <MouseBinding
                                        Command="{x:Static local:PivotGridEditHelper.StartEdit}"
                                        CommandParameter="{Binding ElementName=edit}"
                                        MouseAction="LeftClick" />
                                </dxe:TextEdit.InputBindings>
                            </dxe:TextEdit>
                        </DataTemplate>
                    </dxpg:PivotGridField.CellTemplate>
                </dxpg:PivotGridField>
                <dxpg:PivotGridField
                    x:Name="fieldYear"
                    AllowFilter="False"
                    Area="ColumnArea"
                    Caption="Year"
                    FieldName="OrderDate"
                    GroupInterval="DateYear" />
                <dxpg:PivotGridField
                    x:Name="fieldCategoryName"
                    Area="RowArea"
                    AreaIndex="0"
                    Caption="Category"
                    FieldName="CategoryName" />
                <dxpg:PivotGridField
                    x:Name="fieldProductName"
                    Area="RowArea"
                    AreaIndex="1"
                    Caption="Product"
                    FieldName="ProductName" />
                <dxpg:PivotGridField
                    Area="DataArea"
                    Caption="Percent Of Column"
                    CellFormat="p"
                    FieldName="ExtendedPrice"
                    Name="fieldExtendedPrice2"
                    SummaryDisplayType="PercentOfColumn" />
            </dxpg:PivotGridControl.Fields>
        </dxpg:PivotGridControl>
    </Grid>

</dx:ThemedWindow>

using System;
using System.Collections.ObjectModel;
using System.Windows;
using DevExpress.Xpf.Core;
using DevExpress.Xpf.PivotGrid;

namespace HowToEditCell {
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : ThemedWindow {

        public ObservableCollection<MyOrderRow> OrderSourceList { get; set; }

        public MainWindow() {
            InitializeComponent();
        }

        void Window_Loaded(object sender, RoutedEventArgs e) {
            OrderSourceList = DatabaseHelper.CreateData();
            pivotGridControl1.DataSource = OrderSourceList;
            pivotGridControl1.BestFit();
        }

        void pivotGridControl1_OnCellEdit(DependencyObject sender, PivotCellEditEventArgs args) {
            PivotGridControl pivotGrid = (PivotGridControl)sender;
            PivotGridField fieldExtendedPrice = pivotGrid.Fields["ExtendedPrice"];
            PivotDrillDownDataSource ds = args.CreateDrillDownDataSource();
            decimal difference = args.NewValue - args.OldValue;
            decimal factor = (difference == args.NewValue) ? (difference / ds.RowCount) : (difference / args.OldValue);
            for(int i = 0; i < ds.RowCount; i++) {
                decimal value = Convert.ToDecimal(ds[i][fieldExtendedPrice]);
                decimal newValue = (value == 0m) ? factor : value * (1m + factor);
                ds.SetValue(i, fieldExtendedPrice, newValue);
            }
        }
    }
}

Imports System
Imports System.Collections.ObjectModel
Imports System.Windows
Imports DevExpress.Xpf.Core
Imports DevExpress.Xpf.PivotGrid

Namespace HowToEditCell
    ''' <summary>
    ''' Interaction logic for MainWindow.xaml
    ''' </summary>
    Partial Public Class MainWindow
        Inherits ThemedWindow

        Public Property OrderSourceList() As ObservableCollection(Of MyOrderRow)

        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub Window_Loaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
            OrderSourceList = DatabaseHelper.CreateData()
            pivotGridControl1.DataSource = OrderSourceList
            pivotGridControl1.BestFit()
        End Sub

        Private Sub pivotGridControl1_OnCellEdit(ByVal sender As DependencyObject, ByVal args As PivotCellEditEventArgs)
            Dim pivotGrid As PivotGridControl = CType(sender, PivotGridControl)
            Dim fieldExtendedPrice As PivotGridField = pivotGrid.Fields("ExtendedPrice")
            Dim ds As PivotDrillDownDataSource = args.CreateDrillDownDataSource()
            Dim difference As Decimal = args.NewValue - args.OldValue
            Dim factor As Decimal = If(difference = args.NewValue, (difference / ds.RowCount), (difference / args.OldValue))
            For i As Integer = 0 To ds.RowCount - 1
                Dim value As Decimal = Convert.ToDecimal(ds(i)(fieldExtendedPrice))
                Dim newValue As Decimal = If(value = 0D, factor, value * (1D + factor))
                ds.SetValue(i, fieldExtendedPrice, newValue)
            Next i
        End Sub
    End Class
End Namespace

</dxpg:PivotGridField.DataBinding>
<dxpg:PivotGridField.CellTemplate>
    <DataTemplate>