using DevExpress.XtraGrid;
//...
GridView View = gridView1;
// Create and setup the first summary item.
GridGroupSummaryItem item = new GridGroupSummaryItem();
item.FieldName = "ProductID";
item.SummaryType = DevExpress.Data.SummaryItemType.Count;
item.DisplayFormat = "Count = {0}";
item.Tag = "Count by ProductID";
// Add the summary item to the collection
view.GroupSummary.Add(item);
// Create and setup the second summary item
GridGroupSummaryItem item1 = new GridGroupSummaryItem();
item1.FieldName = "UnitPrice";
item1.SummaryType = DevExpress.Data.SummaryItemType.Sum;
item1.DisplayFormat = "Sum = {0:c2}";
item1.ShowInGroupColumnFooter = View.Columns["UnitPrice"];
item1.Tag = "Sum by UnitPrice";
// Add the summary item to the collection
view.GroupSummary.Add(item1);

Imports DevExpress.XtraGrid
'...
Dim View As GridView = GridView1
' Create and setup the first summary item.
Dim item As GridGroupSummaryItem = New GridGroupSummaryItem
item.FieldName = "ProductID"
item.SummaryType = DevExpress.Data.SummaryItemType.Count
item.DisplayFormat = "Count = {0}"
item.Tag = "Count by ProductID"
' Add the summary item to the collection
view.GroupSummary.Add(item)
' Create and setup the second summary item
Dim item1 As GridGroupSummaryItem = New GridGroupSummaryItem
item1.FieldName = "UnitPrice"
item1.SummaryType = DevExpress.Data.SummaryItemType.Sum
item1.DisplayFormat = "Sum = {0:c2}"
item1.ShowInGroupColumnFooter = View.Columns("UnitPrice")
item1.Tag = "Sum by UnitPrice"
' Add the summary item to the collection
view.GroupSummary.Add(item1)

using DevExpress.XtraGrid.Views.Base;

private void gridView1_FocusedRowChanged(object sender, FocusedRowChangedEventArgs e) {
   GridView currentView = sender as GridView;         
   // The group row's handle.
   int groupRowHandle;         
   if(e.FocusedRowHandle > 0) groupRowHandle = currentView.GetParentRowHandle(e.FocusedRowHandle);
   else groupRowHandle = e.FocusedRowHandle;
   if(!currentView.IsGroupRow(groupRowHandle)) return;

   // Get group summary values.
   Hashtable ht = currentView.GetGroupSummaryValues(groupRowHandle);
   Text = "";
   // Iterate through group summaries.
   foreach(DictionaryEntry entry in ht) {            
      GridGroupSummaryItem sumItem = entry.Key as GridGroupSummaryItem;
      object val = entry.Value;
      // Get the summry item's Tag property and summary value.
      Text += sumItem.Tag.ToString() + ": " + val.ToString() + "\t";            
   }
}

Imports DevExpress.XtraGrid.Views.Base

Private Sub GridView1_FocusedRowChanged(ByVal sender As Object, _
ByVal e As FocusedRowChangedEventArgs) _
Handles GridView1.FocusedRowChanged
   Dim currentView As GridView = CType(sender, GridView)
   ' The group row's handle.
   Dim groupRowHandle As Integer
   If (e.FocusedRowHandle > 0) Then
      groupRowHandle = currentView.GetParentRowHandle(e.FocusedRowHandle)
   Else
      groupRowHandle = e.FocusedRowHandle
   End If
   If Not currentView.IsGroupRow(groupRowHandle) Then Return

   ' Get group summary values.
   Dim ht As Hashtable = currentView.GetGroupSummaryValues(groupRowHandle)
   Text = ""
   ' Iterate through group summaries.
   Dim entry As DictionaryEntry
   For Each entry In ht
      Dim sumItem As GridGroupSummaryItem = entry.Key
      Dim val As Object = entry.Value
      ' Get the summry item's Tag property and summary value.
      Text += sumItem.Tag.ToString() + ": " + val.ToString() + "\t"
   Next
End Sub