A sales management system, comprising: a first device including a first processor that is configured to detect a customer moving an item of merchandise in an extraction direction away from a merchandise display; a second device including a second processor that is configured to detect movement of an item of merchandise from the merchandise display and determine a movement direction thereof; and a third processor that is configured to: determine whether the extraction and movement directions are substantially identical when the first processor detects the customer moving an item away from the merchandise display and the second processor detects movement of an item from the merchandise display at substantially the same time, and determine the item as a first merchandise to be purchased by the customer when the extraction and movement directions are determined to be substantially identical, characterized in that the first device further includes a first clock, and the first processor is further configured to acquire a first time from the first clock when the customer moving the item of merchandise away from the merchandise display is detected, the second device further includes a second clock, and the second processor is further configured to acquire a second time from the second clock when movement of the item of merchandise from the merchandise display is detected, the first clock and the second clock are synchronized, the first device and the second device are communicatively coupled to a communication network, the third processor is further configured to acquire, via the communication network, the extraction direction and the first time from the first device and the movement direction and the second time from the second device, to calculate a difference between the first and second times, and to, when the difference between the first and second times is within a predetermined range, determine that the first processor detects the customer moving the item away from the merchandise display and the second processor detects movement of the item from the merchandise display at substantially the same time, the determining comprising calculating an angular deviation between the extraction and movement directions is within a predetermined range. a first device including a first processor that is configured to detect a customer moving an item of merchandise in an extraction direction away from a merchandise display; a second device including a second processor that is configured to detect movement of an item of merchandise from the merchandise display and determine a movement direction thereof; and a third processor that is configured to: determine whether the extraction and movement directions are substantially identical when the first processor detects the customer moving an item away from the merchandise display and the second processor detects movement of an item from the merchandise display at substantially the same time, and determine the item as a first merchandise to be purchased by the customer when the extraction and movement directions are determined to be substantially identical, determine whether the extraction and movement directions are substantially identical when the first processor detects the customer moving an item away from the merchandise display and the second processor detects movement of an item from the merchandise display at substantially the same time, and determine the item as a first merchandise to be purchased by the customer when the extraction and movement directions are determined to be substantially identical, characterized in that the first device further includes a first clock, and the first processor is further configured to acquire a first time from the first clock when the customer moving the item of merchandise away from the merchandise display is detected, the second device further includes a second clock, and the second processor is further configured to acquire a second time from the second clock when movement of the item of merchandise from the merchandise display is detected, the first clock and the second clock are synchronized, the first device and the second device are communicatively coupled to a communication network, the third processor is further configured to acquire, via the communication network, the extraction direction and the first time from the first device and the movement direction and the second time from the second device, to calculate a difference between the first and second times, and to, when the difference between the first and second times is within a predetermined range, determine that the first processor detects the customer moving the item away from the merchandise display and the second processor detects movement of the item from the merchandise display at substantially the same time, the determining comprising calculating an angular deviation between the extraction and movement directions is within a predetermined range.