Before we used RDC to create and configure reports at runtime, but when the change CR 2008, we had to change RAS DRC.
The problem is that fails to modify the RoundingFormat property by always keeping rounding to 2 decimal places (crRoundingTypeRoundToHundredth), so if you do I setup another kind of rounding is not saved and removed in the preview.
Example where crFld is a FiledObject object:
crFld.FieldFormat.CommonFormat.EnableSystemDefault = False
crFld.FieldFormat.NumericFormat.RoundingFormat = CrRoundingTypeEnum.crRoundingTypeRoundToTenBillionth
crFld.FieldFormat.NumericFormat.NDecimalPlaces = 4
Set rounding to four decimal places but rounded to two decimal places.