Rounding to the nearest 10 or 100

Rounding replaces a number with the nearest ten or hundred. Find the deciding digit — the ones digit when rounding to 10, the tens digit when rounding to 100. If it is 5 or more, round up; if it is less than 5, round down. 45 rounds up to 50 because the 5 rounds up, and 43 rounds down to 40 because 3 is under 5. Decide in one step: do not round to 10 first and then to 100.