Calculate the amount that you are supposed to enter on a particular line without rounding. For example, if you are entering income from taxable interest and you earned $120.30 from Bank A and $234.40 from Bank B, you would calculate the amount to be entered to be $354.70.
Round the calculated amount up to the nearest dollar if the number of cents equals 50 or more. For example, if you were supposed to enter $354.70, enter $355.
Round the calculated amount down to the nearest dollar if the number of cents is below 50. For example, if the amount you are supposed to enter equals $164.29, the IRS allows you to enter $164.
Repeat the process each time you enter an amount onto your tax return. Remember that if you round once, you must round every time.