Making a change to the way charges are handled, the system originally worked such...

Making a change to the way charges are handled, the system originally worked such that if a borrower owed more than $5 issues werent allowed. This worked fine except that often borrowers wish to borrows say 3 pay videos at $2 each, then 2 books say. The three pay videos rack up charges of $6 and then they cant issue the books until that is paid.
Reworked so that it cares about previous charges, not the ones accrued during current issue process.