Did you search the forum, manual, internet for rounding? There seems to be a thread that answers yoiur question and it was in progress since you started on the forum so you will have read it - you do read ALL posts do you not?.

Posted: Wed May 25, 2011 11:12 am Post subject: Reply to: Rounding off the rate value

and what should be the result for 12345.015

ask the powers of Your organization about the rounding rule be used

usually the round half to even rule is used

quoted from wikipedia under the fair use assumption
Round half to even

Quote:

A tie-breaking rule that is even less biased is round half to even, namely
If the fraction of y is 0.5, then q is the even integer nearest to y.
Thus, for example, +23.5 becomes +24, +22.5 becomes +22, −22.5 becomes −22, and −23.5 becomes −24.
This method also treats positive and negative values symmetrically, and therefore is free of overall bias if the original numbers are positive or negative with equal probability. In addition, for most reasonable distributions of y values, the expected (average) value of the rounded numbers is essentially the same as that of the original numbers, even if the latter are all positive (or all negative). However, this rule will still introduce a positive bias for even numbers (including zero), and a negative bias for the odd ones.
This variant of the round-to-nearest method is also called unbiased rounding (ambiguously, and a bit abusively), convergent rounding, statistician's rounding, Dutch rounding, Gaussian rounding, or bankers' rounding. This is widely used in bookkeeping.
This is the default rounding mode used in IEEE 754 computing functions and operators.

the average of two numbers will be preserved
truncation
22.5 ==> 22
23.5 ==> 23
the averages
23 vs. 22.5

half to even
22.5 ==> 22
23.5 ==> 24
the averages
23 vs. 23

meditate better on the rules before worrying about the minutiae of the iomplentation !