Report of Tuition Collected per class by date

I'd like to have a report that shows me sorted by the class, how much tuition was received for that class for each month? I do not want it to include the registration fee; only the tuition received. We often times (with Tippi Toes), have to pay daycares or schools a percentage of the tuition every month. Right now, there is not an easy way to determine (without manual work) what the tuition was that was collected in order to figure out what we have to pay that facility each month.