MonkeyPatch roundHalfToEven (Banker round)

float.rb

##
 # MonkeyPatch roundHalfToEven (Banker round)
 #
 # Solve most of floating binary point problems, and round
 # to the specified decimal using banker round for financial
 # calculations. Half fraction between number are rounded to 
 # the nearest even number.
 #
 # @author Jeremy Trufier <[email protected]>
 # @copyright Storific 2012
 ##

class Float
  def roundHalfToEven(d = 0)
    d = 10 ** d
    n = self * d
    t = n.to_i
    f = (n - t).abs
    
    return t.to_f / d if f < 0.5 || f === 0.5 && t % 2 === 0
    return (t + (self/self.abs).to_i).to_f / d
  end
end