Taking photos one at a time (e.g. two bank slips for a split payment)? Each one adds to the list below --
just tap Choose Files again for the next slip.
Switching to a real payment method -- attach proof of payment before saving.
COD sales don't need a slip yet -- you'll confirm payment received once collected.
Cash sales don't need a digital slip.
Deli Service payment is collected by the delivery service, not you -- no slip needed. You'll confirm payment received once they remit it.