@Override
  public BigDecimal multiply(BigDecimal bd1, BigDecimal bd2) {
    return (bd1 == null || bd2 == null)
      ? null
      : bd1.multiply(bd2).setScale(2, RoundingMode.HALF_EVEN);
  }
ColumnInterpreter for doing Aggregation's with BigDecimal columns. This class is required at the
RegionServer also.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/coprocessor/BigDecimalColumnInterpreter.java