Not exactly, its was 4.2% of your wages up to the taxable wage base
2011 wage base was $106,800 for a max. tax of $4,485.60
2012 wage base was $110,100 for a max. tax of $4,624.20
If you make less that the wage base you are taxed less than the max, if you made more you were taxed the max
I only used 84,00/yr because that’s what you make if 140/month is 2% of your salary