Unless I have confused myself Tendered Amount returns the total amount of money tendered even is multiple payments.
Any change we could get an additional value for payment processed - maybe Tendered Payment to show the amount actually tendered in that payment processed?
Ticket Total = £25
Payment of £10 made
Payment of £50 made
The values currently would be;
Tendered Amount = £60
Processed Amount = £25
So with a change due message on payment processed (remaining total= 0 constraint) on the second payment would be;
£60 tendered however £50 was tendered as £10 had already been taken.