A transaction system includes a commodity registration machine and a check-out machine. The commodity registration machine includes an input device and a processor. The processor determines whether or not whether or not a predetermined condition for permitting check-out processing at the commodity registration machine is satisfied. The processor enables the input device to accept selection of either one of the check-out processing at the commodity registration machine or the check-out processing at the check-out machine if it is determined that the predetermined condition is satisfied.