Hello, Shanti,
RadGridView offers the GroupSummaryEvaluate event where you have access to the calculated value according to the values that are stored in the respective cells. Thus, you can format what exactly is displayed in the summary cell. More information is available here: https://docs.telerik.com/devtools/winforms/controls/gridview/rows/summary-rows
Please refer to the following code snippet:
Private Sub RadGridView1_GroupSummaryEvaluate(ByVal sender As Object, ByVal e As GroupSummaryEvaluationEventArgs)
If e.SummaryItem.Name = "UnitPrice" Then
e.FormatString = String.Format("₹ {0}", e.Value)
End If
End Sub

I hope this information helps. Should you have other questions please let me know.
Regards,
Nadya
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