Round a number even (a.k.a. banker's rounding)
Level: Beginner (score: 2)
Bankers Rounding is an algorithm for rounding quantities to integers, in which numbers which are equidistant from the two nearest integers are rounded to the nearest even integer. Thus, 0.5 rounds down to 0; 1.5 rounds up to 2. - source
Complete the function below that takes an float, returning it rounded even.