If your answer is initially a decimal like .03571, first convert it into a % by multiplying the decimal by 100. Essentially, you're moving the decimal 2 places to the right and attaching the % sign.
.03571 = 3.571%
Now, to round this % to the nearext hundredth, you need to inspect the value of the position just to the right of hundredths place. That would be thousandths place. In this example, that would be the 1.
Since 1 < 5, you make no changes to the hundredths place, and your rounded % = 3.57% to the nearest hundredth.
Had the thousandths place been > or = 5, we would've added one to hundredths place.
.03575 = 3.575% ~ 3.58%