a SSRS 2008 problem: How to sum with a condition

I have a SSRS report in which there is two column Current_Product and TempAnnSaving. Current_product has value current product and their match. that means each current product have a match row or it may be more than one row. Eac开发者_StackOverflow社区h match row has a TempAnnSaving value in TempAnnSaving column. Now at the end of the report I have to show the total sum of TempannSaving, but there is a condition for sum--I have to sum only first match of each current product.