How to add total in Gridview merge rows.

Sno    Date   Partyname   Meattye   Weight  Rate   Total    DCNO      
 1    26/10     A           Chicken  12      150    1800     1546      
 2    26/10     A           Mutton   10      150    1500     1546 

      
 3    26/10     A           Keema    5       100     500     1547 
     
 4    26/10     C           Chicken  12      150    1800     1548 
 
 5    26/10     D           Chicken  12      150    1800     1549 
 6    26/10     D           Beef     10      150    1500     1549      

My desired O/P is( Only merge and add #Total Feild based on  DCNO)


 Sno    Date   Partyname   Meattye   Weight  Rate   Total    DCNO      
 1    26/10     A           Chicken  12      150     3300    1546      
 2    26/10     A           Mutton   10      150             1546 
      
 3    26/10     A           Keema    5       100     500     1547
      
 4    26/10     C           Chicken  12      150    1800     1548 
 
 5    26/10     D           Chicken  12      150             1549 
 6    26/10     D           Beef     10      150    3300     1549 

protected void GVDCNoConfirm_RowDataBound(object sender, GridViewRowEventArgs e)
   {
       var thisRow = e.Row;
       if (e.Row.RowType == DataControlRowType.DataRow)
       {



         for (int rowIndex = GVDCNoConfirm.Rows.Count - 2; rowIndex >= 0; rowIndex--)
           {

               GridViewRow gvRow = GVDCNoConfirm.Rows[rowIndex];
               GridViewRow gvPreviousRow = GVDCNoConfirm.Rows[rowIndex + 1];



               for (int cellCount = 8; cellCount < gvRow.Cells.Count;
                                                             cellCount++)
               {


                   if (gvRow.Cells[cellCount].Text ==
                                          gvPreviousRow.Cells[cellCount].Text)
                   {


                       if (gvPreviousRow.Cells[cellCount].RowSpan < 2)
                       {
                           float currentvalue = 0;
                           currentvalue = Convert.ToSingle(gvRow.Cells[7].Text);
                           gvRow.Cells[7].Text = Convert.ToString(currentvalue + Convert.ToSingle(gvPreviousRow.Cells[7].Text));
                           gvRow.Cells[cellCount].RowSpan = 2;
                           gvRow.Cells[7].RowSpan =2;



                       }
                       else
                       {
                           gvRow.Cells[cellCount].RowSpan =
                          gvPreviousRow.Cells[cellCount].RowSpan + 1;
                           gvRow.Cells[7].RowSpan =
                         gvPreviousRow.Cells[7].RowSpan + 1;

                       }
                       gvPreviousRow.Cells[cellCount].Visible = false;
                       gvPreviousRow.Cells[7].Visible = false;



                   }
               }



           }




       }
   }