As long as the calculation type moves the money into/out of the proper account(s) it should. I’ll have to play with it.
With regards to payment processors, one should be able to prompt for a tip and add a calculation. So, let’s say there’s a $10 cash tip. A calculation for tip is added for $10, but then also a payment for $10 would need to be added to balance the drawer.
Q did something with a payment processor to store CC details.
I haven’t parsed the ticket object to see what data is passed. If it contains a ticket identifier, one could use the API to open the terminal ticket, add the needed calculations/payments, then close it.
I have a friend leaving the island today. If I don’t drink a whole lot, I’ll work on this later and see what can be done.