Caluclating the sum of all the rows in a datatable and place it in the last row

  // here 'm datatable from cache which is already stored, u can careate ur own datatable    

                DataTable NewGdt = (DataTable)HttpRuntime.Cache[cachekey];

                int casesum = 0;
                int pratesum = 0;
                int appamtsum = 0;
                DataTable dt = null;

                DataTable StatusDT = null;
                OleDbCommand cmd = null;
                OleDbDataAdapter StatusAdpt = null;

                DataRow[] rows = NewGdt.Rows;

                dt = new DataTable();
                dt.Columns.Add("SL No");
                dt.Columns.Add("DISTRICT");
                dt.Columns.Add("PKG_CATEGORY");
                dt.Columns.Add("CASES");
                dt.Columns.Add("AMT");
                dt.Columns.Add("TOTALAPPAMOUNT");

                foreach (DataRow dr in rows)
                {

                    object[] row = dr.ItemArray;

                    dt.Rows.Add(row);

                   // here 'm getting sum on each row

                    casesum = casesum + Convert.ToInt32(dr["CASES"]);
                    pratesum = pratesum + Convert.ToInt32(dr["AMT"]);
                    appamtsum = appamtsum + Convert.ToInt32(dr["TOTALAPPAMOUNT"]);
                }

                DataRow newrow = dt.NewRow();

                newrow["PKG_CATEGORY"] = "Total";
                newrow["CASES"] = casesum.ToString();
                newrow["AMT"] = pratesum.ToString();
                newrow["TOTALAPPAMOUNT"] = appamtsum.ToString();
                dt.Rows.Add(newrow);

                /// 'm binding final table to gridview

                ChildGridview.DataSource = dt;
                ChildGridview.DataBind();
                int count = ChildGridview.Rows.Count;
                ChildGridview.Rows[count - 1].Font.Bold = true;