How to sum a column in repeater control

string Total="";
protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
              if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {      
            //gives the sum in string Total.                 
            Total += Convert.ToDecimal(DataBinder.Eval(e.Item.DataItem, "column_name"));
            }
 else if (e.Item.ItemType == ListItemType.Footer)
{
 // The following label displays the total
 Label1.Text = TotalCost;
}