banker's rounding

For banking or scientific purposes it is often considered correct to round something 0.5 to the nearest even number, i.e. not always upward). For instance, 5.5 rounds to 6, but 12.5 rounds to 12. This method avoids introducing a bias to a large set of numbers, by rounding up more or less as often as rounding down. Unfortunately, at a lower level, it is often taught to round something 0.5 upward all the time.