Employee Gross Ups - receiving Net of $1.00 more than actual Net Amount should be.

Oracle has not been able to resolve this issue and I have drained my thinking cap dry.  This does not happen to all Gross Ups - sometimes a small percent, sometimes a larger percent - all within one company. 

The User is entering a Gross Up for Safety Bonus - very simple Pay Type setup, no special rules.  When the User clicks the Calculate in Interims, the resulting Net Pay is $1.00 more than the Net Amount entered.  Occasionally, if the user clicks calculate, the system adds another dollar, most of the time it does not.  I know it sounds crazy but it happens on some employees every time Gross Ups are entered.