According to Wikipedia when rounding a negative number, you round the absolute number. So by that reasoning, -3.5 would be rounded to -4. But when I use java.lang.Math.round
Turns out the convention is to round up. I guess Wikipedia is fallible. Turns out Microsoft got it wrong, though, as they round it to -4 as well, which is not convention (I checked with someone who has a PhD in math).