Referring this says:
Rounding mode to round towards the "nearest neighbor" unless both
neighbors are equidistant, in which case, round towards the even neighbor.
Behaves as for RoundingMode.HALF_UP if the digit to the left of the
discarded fraction is odd; behaves as for RoundingMode.HALF_DOWN if it's
even. Note that this is the rounding mode that statistically minimizes
cumulative error when applied repeatedly over a sequence of calculations.
It is sometimes known as "Banker's rounding," and is chiefly used in the
USA. This rounding mode is analogous to the rounding policy used for float
and double arithmetic in Java.
Example:
Input -> rounded
5.5 -> 6
2.5 -> 2
1.6 -> 2
1.1 -> 1
1.0 -> 1
-1.0 -> -1
-1.1 -> -1
-1.6 -> -2
-2.5 -> -2
-5.5 -> -6
So it rounds towards nearest value and if both are equidistant then it rounds towards an even number.
