Rounding mode:
http://java.sun.com/javase/6/docs/api/java/math/RoundingMode.html
Code Example：
double result1 = new BigDecimal(String.valueOf(12.115)).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
double result2 = new BigDecimal(String.valueOf(-12.115)).setScale(2, BigDecimal.ROUND_CEILING).doubleValue();
