how to show empty row on grid view in asp.net

Fill your remaining datasource rows to null rows.
Try this code
 int rowcount = dt.Rows.Count;
        int remainingCount = 10 - (rowcount % 10) ;
        for (int i = 0; i < remainingCount; i++)
        {
            DataRow row = dt.NewRow();
            dt.Rows.Add(row);
        }