How to add the summary value with title in a single cell in WinForms GridGroupingControl?
Summaries
By default, the title for the summary row will be added in the first column. The summary value and the title will not be added in a single cell when the datasource has single column. In order to display the SummaryValue with its title, the Style property of GridColumnDescriptor can be set as GridSummaryStyle.FillRow and set the respective format of the summary value with title by using Format property.
C#
//To add the summary for a column
summaryColumnDescriptor = new GridSummaryColumnDescriptor("TotalSum");
summaryColumnDescriptor.SummaryType = SummaryType.Int32Aggregate;
summaryColumnDescriptor.Format = "Total summary: {Sum}";
summaryColumnDescriptor.DataMember = "CategoryID";
summaryColumnDescriptor.Style = GridSummaryStyle.FillRow;
GridSummaryRowDescriptor summaryRowDescriptor = new GridSummaryRowDescriptor();
//To add summary columns to summary row
summaryRowDescriptor.SummaryColumns.Add(summaryColumnDescriptor);
//To add summary row to the TableDescriptor
this.gridGroupingControl1.TableDescriptor.SummaryRows.Add(summaryRowDescriptor); VB
'To add the summary for a column
summaryColumnDescriptor = New GridSummaryColumnDescriptor("TotalSum")
summaryColumnDescriptor.SummaryType = SummaryType.Int32Aggregate
summaryColumnDescriptor.Format = "Total summary: {Sum}"
summaryColumnDescriptor.DataMember = "CategoryID"
summaryColumnDescriptor.Style = GridSummaryStyle.FillRow
Dim summaryRowDescriptor As New GridSummaryRowDescriptor()
'To add summary columns to summary row
summaryRowDescriptor.SummaryColumns.Add(summaryColumnDescriptor)
'To add summary row to the TableDescriptor
Me.gridGroupingControl1.TableDescriptor.SummaryRows.Add(summaryRowDescriptor) The
Screenshot below illustrates the summary value with the summary title

Samples:
Reference Link: Summaries