Mock Transaction App - Does one exist?

[Jdub41]

I am an educator who wants his students to operate a mock e-commerce platform.  However, I cannot find a dummy/mock/fake transaction app that I can use.  The design element is no problem for the students, but due to district rules, actual money cannot be used.  Is there an app - or backward way - to allow the students to process experimental transaction, so they can learn how to manage the e-commerce platform.  I would love help with this.  Many thanks.