The customer sees a receipt. Your business needs more: the right stock movement, the right tender or receivable, and accounting evidence that can be reviewed later.
Start by tracing one ordinary sale end to end. Who enters it? Who collects payment? Where does the stock come from? How is an error corrected?
A connected workflow makes those handovers explicit. In your ObboPOS demo, ask to see held sales, cashier handover and the posted stock and journal evidence, not just a beautiful checkout screen.