A commodity sales data processing apparatus includes an image processor and a controller. The image processor captures an image including a symbol. The symbol includes discount information relating to a discount on a price of a commodity. The controller acquires commodity information that uniquely specifies the commodity. The controller extracts a region from the image captured by the camera. The region includes the symbol. The controller transmits, to a server, an image of the region extracted by the controller. The controller acquires, from the server, the discount information based on the image transmitted to the server. The controller registers the commodity information acquired by the controller and a discounted price of the commodity based on the discount information acquired by the controller in association with each other.