More like time/date, UPC, quantity, item description, price, coupons, sale discounts, sales tax, rebate info, clerk info, customer info, payment info, and more. Times dozens of items per receipt, times dozens of registers. All continually operating 12+ hours a day. All needing low-latency access to master databases, credit card servers, and banks.

Trust me, retail is big. Like "Big Data" big. There is more data there than you think. ;)