public Style PrintFixedTotalSummaryStyle { get; set; }

Public Property PrintFixedTotalSummaryStyle As Style

<Window xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        xmlns:dxgt="http://schemas.devexpress.com/winfx/2008/xaml/grid/themekeys"
        xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors">
    <Window.Resources>
        <Style x:Key="customPrintFixedTotalSummaryStyle" 
               BasedOn="{StaticResource {dxgt:TableViewThemeKey ResourceKey=DefaultPrintFixedTotalSummaryStyle}}" 
               TargetType="dxe:TextEdit">
            <Setter Property="HorizontalContentAlignment" Value="Center" />
            <Setter Property="BorderBrush" Value="White" />
            <Setter Property="Background" Value="White"/>
            <Setter Property="BorderThickness" Value="1" />
        </Style>
    </Window.Resources>

    <dxg:GridControl ...>
    ...
        <dxg:GridControl.View>
            <dxg:TreeListView ShowFixedTotalSummary="True"
                              PrintFixedTotalSummaryStyle="{StaticResource customPrintFixedTotalSummaryStyle}"
                              .../>
        </dxg:GridControl.View>
    </dxg:GridControl>
</Window>