Hiding formula results in tables if no I/P on that row

I am trying to produce a monthly bank statement check sheet. Showing Income and outgoings, with a running total coloum down the right side. At the moment the total is displayed all the way to the bottom of the page, even if there is no IN or Out on the Row. (ie displays the same answer to the last sum the rest of the way down the page)I would like the total to be blank unless there is an entry on that line. Im sure there must be an easy answer but im affraid I cant find it and would be grateful for any help.