Retail POS is the billing-counter software of a retail chain, together with the store system behind it, which holds the prices, the stock and the day's takings for every till. POS means point of sale. The store system behind the counter is called the back office. Supermarket chains, clothing chains and pharmacy chains all use it.
The general idea of billing software is explained on the page on point of sale (POS) software. This page covers what a large retailer needs on top of it. A small shop has one counter. A supermarket chain may have 400 tills in 60 stores, and all of them must charge the same price for the same product at the same time.
Take, for example, a supermarket chain with 60 stores across Tamil Nadu. On Thursday, the head office decides to cut the price of a 5 kg bag of rice from ₹420 to ₹389 for the weekend. Such a price often comes from price and promotion optimisation software. That night, the head office system sends the new price to the back office of every store. Each back office passes it to its tills. On Friday morning, every till in every store charges ₹389. On Monday morning, the old price returns automatically.
During the day, each till sends every sale to the store's back office. The back office reduces the stock of each item sold. At closing time, it adds up the day's takings, separately for cash, UPI and cards. The store manager counts the cash in the drawers and checks it against that total. The back office then sends the store's sales and stock to the head office. There, the data is used to reorder stock. Out-of-stock detection software also reads it, to find empty shelves.
Two features matter more in a large chain than in a single shop. First, the tills must keep working when the internet fails. So each till keeps its own copy of the prices, and sends its sales later, when the connection returns. Second, every bill must follow the rules for GST, the tax on goods and services. So the software prints each item's tax rate on the bill, and adds up the tax for the store's returns.
Large retailers also want the counter to know about online orders. A customer may buy a shirt online and return it in a store. The store's till must find the online order and refund it. Running the stores and the website as one business, with one stock record and one customer record, is called unified commerce.
The counter itself is changing. A self-checkout kiosk lets the shopper scan alone, and scan and go lets the shopper scan on a phone. Both still send each sale to the same back office.