And the salesman's terminal will usually be a laptop linked to his central host over the internet via an Air card. I've never seen a salesman use a bar code reader, all his products are available to him on his laptop, either as a recently downloaded Access database or live from the host. Competition in this area is fierce, and the salesman who gets his order in fastest can deliver sooner.
POS electronics stays pretty close to the cutting edge of technology. Most POS terminals are usually Pentium P4 class PC's with one ore two special adaptor cards to provide more serial I/O.
For instance, if you were to open up the cabinet in one of those grocery store self checkout units you will find the whole thing is run by one P4 PC. Everything in that station interfaces with the PC, the touch screen, scanner/scale, bag scale, color video camera, EFT device, coin acceptors and dispensers, bill acceptors and dispensers, and soon a dual camera system that looks at the bottom of your cart and will identify by image comparison the large bulky items people place there. The PC is linked to the store controller over one standard CAT5 network cable and the controller is linked to the corporate network over either a T1 line or a satallite link.
The POS electronics market is a field where all the really big players are, IBM, NCR, Fujitsu, and Symbol to name just a few.

Just some 'food' for thought,

Hal