<obout:Grid  ShowColumnsFooter="true" OnRowDataBound="RowDataBound"...

    double totalPrice = 0;
    int unitsInStock = 0;
    int unitsOnOrder = 0;
    
    public void RowDataBound(object sender, GridRowEventArgs e)
    {
        if (e.Row.RowType == GridRowType.DataRow)
        {
            totalPrice += double.Parse(e.Row.Cells[2].Text);
            unitsInStock += int.Parse(e.Row.Cells[3].Text);
            unitsOnOrder += int.Parse(e.Row.Cells[4].Text);
        }
        else if (e.Row.RowType == GridRowType.ColumnFooter)
        {
            e.Row.Cells[1].Text = "Total:";
            e.Row.Cells[2].Text = "$" + totalPrice.ToString();
            e.Row.Cells[3].Text = unitsInStock.ToString();
            e.Row.Cells[4].Text = unitsOnOrder.ToString();
        }
    }

    Dim totalPrice As Double = 0
    Dim unitsInStock As Integer = 0
    Dim unitsOnOrder As Integer = 0
    
    Sub RowDataBound(ByVal sender As Object, ByVal e As GridRowEventArgs)
        If e.Row.RowType = GridRowType.DataRow Then        
            totalPrice += Double.Parse(e.Row.Cells(2).Text)
            unitsInStock += Int32.Parse(e.Row.Cells(3).Text)
            unitsOnOrder += Int32.Parse(e.Row.Cells(4).Text)
        ElseIf e.Row.RowType = GridRowType.ColumnFooter Then
            e.Row.Cells(1).Text = "Total:"
            e.Row.Cells(2).Text = "$" + totalPrice.ToString()
            e.Row.Cells(3).Text = unitsInStock.ToString()
            e.Row.Cells(4).Text = unitsOnOrder.ToString()
        End If
    End Sub