Money Credits are store credit. They've already been paid for, and aren't considered new revenue. Customers can buy them in a POS transaction to use later on, much like a gift card.

Within the Total Sales Report, the default filter setting is to remove all sales paid for with money credits. This is to avoid double reporting revenue. For example, if someone buys $20 of money credits, then spends those credits on a class worth $20, reporting both transactions would total $40.

This default filter removes all transactions where a customer used money credits to purchase other things like class bookings or memberships.