Adding a product
Each product needs a name, a selling price, and a category. Add a barcode if you scan, a cost price if you want margin reporting, and the tax rate that applies.
Categories matter more than they look
Categories are how you find things later and how reports group them. A shop with hundreds of products and no categories has reports that tell it nothing.
Barcodes
If you scan at the till, put the real barcode on the product. Scanning is faster and removes the commonest error at the counter: ringing up the wrong similar-looking item.
Why this setup matters
All of it exists so the till can be fast. A cashier should scan, take money, and move on. They should not be deciding prices, looking up tax rates, or wondering whether something is in stock.
Keeping stock honest
Stock moves on its own as you sell and as you record purchases — you should rarely type a stock figure by hand.
When you do need to correct one, record it as an adjustment with a reason. "Stock was wrong" with no reason recorded is how shrinkage becomes invisible.
If stock is always low on the same lines, look at whether purchases are being entered when goods arrive. Deliveries recorded late make the till think you have nothing to sell while the boxes sit in the stockroom.
The Kinxso POS manual covers products and stock in full.