Correction from the last post, don't calculate FICA tax on the $55k, calculate it on the $75K gross. This mistake would likely net to the same result though as not using a graduated tax table, so the result would likely be about the same.
EDIT:
Here's a more exact calculation
Gross 76,168
Exemptions/Standard (20,000)
Taxable 56,168
Fed Taxes 7,533 15.00% Marginal
State Taxes 2,808 5.00%
Fica Taxes 5,827 7.65%
Net 60,000
So with a 5% state tax the answer is $76,168