While briefing through this Python course by TIQC (very good course, very interactive, great professor Jake Gober), a question came up in the second video: Why is round(10.5) = 10? I'm not sure if the professor had the chance to talk about it, and I had to look up this strange phenomenon.
It turns out that it is true, that it will round to the closest even choice. So round(10.5) = 10, while round(11.5) = 12. Because those are the closest even numbers to round to.
But what's going on? Apparently it's called Banker's Rounding. It seems to be a unbias way for bankers to deal with rounding numbers, so as not to not over pay or under pay interests.