Round to the nearest tenth. Would 5.21 be rounded to 5.20?
5.20 is wrong, because you are supposed to round to the nearest tenth.
Right. But you don't need the 0. 5.21 = 5.2
To round a number to the nearest tenth, you need to look at the digit in the hundredth place.
In the number 5.21, the digit in the hundredths place is 1. When rounding to the nearest tenth, if the digit in the hundredth place is 5 or greater, you round the digit in the tenths place up by 1. If the digit in the hundredth place is less than 5, you do not change the digit in the tenths place.
In this case, since the digit in the hundredths place is 1, which is less than 5, we do not need to round up. Therefore, 5.21 rounded to the nearest tenth would be 5.2, not 5.20.