system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we round 0.500 up to 1?
gpt
Because you have to round in one direction or the other, and we decided to pick up.

Note this is not universal.  In some financial accounting, you "round towards even".  3.5 would round to 4, but 2.5 would round to 2.  The idea is to try to make the rounding errors cancel out.