Bar code readers, scanners, and price look-up systems have replaced individual prices on items. Price verification consists of periodic simulated purchases at businesses utilizing scanners, or point-of- sale systems, to ensure that consumers are correctly charged. This area has become more important because many or all stores of national chains determine their pricing through a central computer; an error in one store is an error in them all. Items offered on sale are most frequently found to be in error, and the consumer must always be given the item at the lowest posted price.