Yes, both the TabPOS and WinPOS have training modes where you can practice all features without have the transactions saved.

TabPOS - on the log in screen, check the Training option. 

If you have not registered yet, you can also select DEMO and use the pre populated items to get a feel for the application

The WinPOS has a training mode which you access from Windows Start and select the retailcloud application - there is a Training option. Once you complete the training you need to switch back to the Live Mode