有效的BigDecimal舍入到小数点后两位

public static BigDecimal round(BigDecimal d, int scale, boolean roundUp) {  int mode = (roundUp) ? BigDecimal.ROUND_UP : BigDecimal.ROUND_DOWN;  return d.setScale(scale, mode);}round(new BigDecimal("12.390"), 2, true); // => 12.39round(new BigDecimal("12.391"), 2, true); // => 12.40round(new BigDecimal("12.391"), 2, false); // => 12.39round(new BigDecimal("12.399"), 2, false); // => 12.39