This is done via Tool #188 "Cashed Check Fee Configuration."  See below for more information on this feature. 

All check cashing or check negotiation fees (check cashing fees that are charged even if the funds are deposited) are charged on the main Teller Posting screen using the field at the bottom of the screen, which takes away from the cash back amount.  The system will evaluate the entire transaction to determine whether the fee should be charged or not, according to your configuration.