May not have understood, maybe you want to add tips take the deductions then deduct the tips (sort of an in and out)
If so, set up two accounts like accrued holiday.
The first acct is to enter the tips using ~T=I: M=Tips: for input the amount and as a D item or invome acct
The second acct setup the same way using ~T=I: M=Tips deducted, as a C item, to deduct the same tips after deductions are taken off.
See if that works?