Type "CURR - Currency field, stored as DEC" only contains 2 decimal digits?

We have a KF which has a data type of "CURR - Currency field, stored as DEC" mapped to a R3 field with 3 decimal digits, but "CURR - Currency field, stored as DEC" data type in BW/BI takes up only 2 decimal digits that the last digit of R3 field value is ignored.

Any idea for a workaround?

Thanks!