This feature will work when you cancel order by using Unify Enterprise and transaction is created as Sales Receipt in POS.
Step 1 : On your Unify Enterprise Dashboard, go to "File menu >> Configure Store".
Step 2 : On the Store Setup screen, go to Orders tab.
Step 3 : On the Orders tab, click on Order Processing Settings. Here under the Cancel Order Settings, select Yes or No from the drop down for whether you want create return receipt or not. Click on Save & Continue.