A method for allowing a customer to view and at least partially pay a bill incurred in a bar or a restaurant operating a POS system tracking the bill. The customer operates a mobile computing device running a mobile app communicating with the POS system. The bar or the restaurant has staff. The method includes receiving, via the POS system, check-in data in response to checking-in via the app and payment account data as a security in response to authorizing access to the payment account data via the app. The method includes receiving, via the staff, an order from the customer and associating, via the staff, the order with the payment account data in the POS system. The method includes displaying the bill in real-time via the app. The bill includes the order. The method includes receiving at least partial payment in response to such authorizing via the app.