I always check receipts and fabric before leaving stores. If you don't understand the receipt ASK someone about it. Unfortunately, people are human and make mistakes (some stores rely on a computer inventory system that doesn't completely get the correct price updates, etc.) and not everyone is out to get us. When a discrepancy has occured I have never had an issue. If I feel there is a deliberate mistake I get an immediate refund and walk away. If there is a no refund policy that I find out about AFTER the fact then I make sure I never use that establishment again.