How would you round 8.02

You would round 8.02 down to 8.

Well, if you're rounding to 1 significant figure, which you'll mostly be asked to do,

You look and see which number is the first one which isn't a zero. The most significant. In this example, the 8. You then need to look at the second number, it's a zero. It has no value and doesn't do anything to the 8. The number after that gets rounded down to a zero, it's too far away to effect the 8, and even if it could it's too low.

The answer is 8.

(Sorry if my answer was a bit complicated ...)