A registration apparatus includes a scanner configured to optically read a product code from a product, a communication interface configured to communicate with one or more payment apparatuses associated with the registration apparatus, a display, and a processor. The processor is configured to control the communication interface to transmit registration data including data of one or more product codes read through the scanner for a transaction to a selected one of the one or more payment apparatuses, for processing payment for one or more products registered by the registration apparatus. The processor is also configured to control the display to display a monitoring screen indicating an operational state of a checkout process carried out by the selected one of the one or more payment apparatuses to which the registration data has been transmitted, based on information received from the selected one of the one or more payment apparatuses.