How did this turn out? I am seeing a similar issue with 4.5.5 were a conversion left UDF's defined with a 2 decimal mask (#,##0.00 confirmed) rounding as if the mask were (#,##0). During data entry the grid would reflect the decimals entered and remain on the screen as one moved to additional lines, but after the records were Accepted and the records were recalled the UDF's had been rounded.