“The origin of the term bankers’ rounding is more obscure. If this rounding method was ever a standard in banking, the evidence has proved extremely difficult to find. To the contrary, section 2 of the European Commission report The Introduction of the Euro and the Rounding of Currency Amounts [2] suggests that there had previously been no standard approach to rounding in banking.”

http://en.wikipedia.org/wiki/Rounding#Round-to-even_method

“Rounding mode to round towards the “nearest neighbor” unless both neighbors are equidistant, in which case, round towards the even neighbor. Behaves as for ROUND_HALF_UP if the digit to the left of the discarded fraction is odd; behaves as for ROUND_HALF_DOWN if it’s even. Note that this is the rounding mode that minimizes cumulative error when applied repeatedly over a sequence of calculations.”

http://java.sun.com/j2se/1.5.0/docs/api/java/math/BigDecimal.html#ROUND_HALF_EVEN

Just make sure you don’t mess up on some mundane detail like putting a decimal point in the wrong place.

But seriously, it’s been my opinion for a while that using float or double should cause a compiler warning optionally suppressed by a compiler flag. I believe the only place a typical programmer would run into floats being used correctly would be 3D graphics programming.

A lot of people tried this, most of them got caught when getting greedy :-)