fails:Float#round rounds self to an optionally given precision
fails:Float#round returns self for exceptional values when passed a non-negative precision
fails:Float#round works for corner cases
fails:Float#round returns rounded values for big values
fails(compiler):Float#round raises FloatDomainError for exceptional values when passed a non-positive precision
fails:Float#round raises RangeError for NAN when passed a non-positive precision
