Eighty-five dollars are entered under "wages" and $15 are entered under "payroll taxes." However, it is YOU who earned that $15 dollars to pay the "employer's share." Not only that, but the employer also withholds your "share" of payroll taxes taking another $15 from what you earned. Thus leaving you with a net of $70.
In summary, the employee ends up paying for all payroll taxes because it is his work that generates the revenue the employer uses to pay them.