A sales-data processing device includes: a registering circuit that registers a product and generates registration data; a settlement processing circuit that executes settlement processing using the registration data; a sending circuit that sends the registration data to another sales-data processing device for execution of the settlement processing by the other sales-data processing device using the registration data; and a prohibiting circuit. Once the sales-data processing device has determined that the sending circuit will send the registration data, the prohibiting circuit prohibits the settlement processing circuit from executing the settlement processing before the sending circuit sends the registration data.