You can iterate through all the cells in the column and add the values for each cell. You can then display the total in all cell you want to.
int rowCount = datagridview.Rows.Count;
int columnIndex = datagridview.Columns[columnName].Index;
int sum = 0;
for (int i = 0; i < rowCount; i++)
{
sum += datagridview[columnIndex, i];
}
datagridview[columnIndex, rowCount+1].Value = sum;
This should work.
Thanks,
Rashmi