PURPOSE: To improve the efficiency of inspection and liquidation work in sales data processing by starting print output of tabulation data onto a sales tabulation report when completing collection and tabulation of one block of sales data and by instructing a satellite machine to collect the next block of sales data.

CONSTITUTION: Sales data of each sales article sold and registered by the master machine 1M and each satellite machine 1S is accumulated and stored in its own file 3 for sales registration for each price look up (PLU) code. Further, in the master machine 1M, an 'inspection' or 'liquidation' mode is selected, and when issuing a sales tabulation report is demanded for each PLU code, data that is contained in the first one block b1 stored respectively in file 3 for sales and registration of each satellite machine 1S is tabulated for each PLU code. Furthermore, when the tabulation of a relevant block b1 is completed, printing of the sales tabulation data is started onto the sales tabulation report, and each satellite machine 1S is demanded to collect the next block b2 of sales data. Thus, the efficiency of inspection and liquidation work can be enhanced.