With a web based application all of the items you are looking for will interface easily as keyboard emulation devices except the cash drawer. Drawers are normally connected to a receipt printer directly or to the PC via USB but both of these situations require support from the software specifically for this. For the hardware options I would suggest the Motorola LS2208 scanner, a Magtek Dynamag credit card reader, and a Cherry keyboard. The APG line of cash drawers offer the full range of interfacing options but this will depend on what type of support your web application can provide.