Always have a drawer full of receipts here, as there's a bi-monthly "receipt lottery" where you check the numbers printed on the top of your receipt and get money if they match the draw. Got £70 last month. I know a lot of people don't bother keeping them, but it only takes 5 minutes to check, and I've never got less than £20 or so. One last time round was £25 for a £1 beer
..There is logic behind this, it was introduced to get businesses to comply with tax laws, as customers would demand a receipt to get their "lottery ticket". There's a green, non paper-based version too which stores the numbers on your contactless card, but it's all in Chinese and a terribly designed website, plus I'm leaving soon anyway.