Basically you don't really do either, mostly because when your rounding you mostly just look at the number your rounding to. okay so say your number is like 127 you would round to 100 because your number would've been below 150. And we know that five is the middle of every thing. 10 and the whole number system is made up of tens. So when you have to choose to round you have to go up to the next ten so say your number is 27 since it's above 5 you would round to 30. So if you have 127 it's below the 5 mark (which would be 150) so you would round to 100 because it's below that mark.
