develop a function that allows us to record copying and printing fees.

Would it be possible to develop a function that allows us to keep track of students' printing/copying fees? Here at our library (the New Life Theological Seminary Library) we receive payments for the copy and print-outs that students make.  Sometimes students don't have the money to pay for a copying or printing job, so we write up I.O.U.s on slips of paper.  It seems that (along with overdue book fines) we should be able to record students' printing and copying fees. As it is now, at the end of the semester, we have to manually impose "lock-outs" on students' accounts--lock-outs that they cannot see on their online accounts. Then we get lots of phone calls from students, wanting to know why they cannot access their grades at the end of the term ("Populi says I have no outstanding fees!" when actually they do).