There isn't a way to report these figures 100% accurately on partial payments on an invoice and accounting professionals (and in some cases municipal or national governments) differ in the best treatment.
For example, say that you have an invoice with service and parts. One tax / VAT rate is for service and one for parts. Let's say you take a 50% payment. When reporting on Z-reports, it's impossible to say if that partial payment was 1/2 service and 1/2 parts, or all service and no parts, etc. In this case, RepairShopr doesn't display partial payment tax / VAT calculations until the entire invoice has been paid.