Decimal ROUND_HALF_EVEN Default

[Tim Peters]

[3c273]
> I'm just curious as to why the default rounding in the decimal module is
> ROUND_HALF_EVEN instead of ROUND_HALF_UP.

Because it's the best (numerically "fairest") rounding method for most
people most of the time.

> All of the decimal arithmetic I do is rounded half up and I can't think of
> why one might use round half even.

Because you want better numeric results, or because your application
requires it.  "Half-even" is also called "banker's rounding" in the
United States, because it's required in many (but not all) banking
applications.