Shops and other businesses that sell goods or services against payment by cash or cards, use cash registers with a certified control unit. The purpose of the cash register is to stop tax fraud and protect legitimate businesses. The law on cash registers applies in principle to all organizations that receive payment in cash or card. The control unit that sits connected to the cash register shall be certified. There must also be a manufacturer declaration saying that the cash register and the certified control unit works and is tested together. Only accredited certification bodies are allowed to certify control units. There are certain activities that are not affected, such as taxis, distance- and home selling and goods and slot machines.
Further information is available on the Swedish Tax and Revenue service website. (in Swedish)