Dear POS - Set payment amount default

Problem:

Staff members accidentally choose the payment method before updating amount. This then closes the sale as it is paid in full (payment amount defaults to balance owing). To resolve, the cashier has to refund the sale and then re-process it again, which is time consuming in front of a customer

Proposed Feature:

1) Option in settings to set payment amount to default to $0

2) Ability to 're-open' a sale without having to refund/exchange items