Hidden Cell Value

My problem is I have a payroll spreadsheet. I have figured the Soc. Sec. column using a formula with percentage. When I then subtract the Soc. Amt from the gross pay amt I get a penny off as the calculation does not account for the rounding up of the Soc. Sec. amount. It seems to be using the hidden value with full decimals. How do I fix it to use the displayed value of Soc. Sec.???