Most modern (even the low end) registers allow for saving the transactions to a memory card, or can be polled (or can act as a 'stupid termina' when wired up -- but that requires a lot more software). The low end units typically store the output as ascii; very akin to the format you find on the paper tape; i.e. as would be written to the printer (at the end of the day, or as a carbon copy). Some, e.g. Sharp, have a more readily parsed format, basically CSV, which is easier to handle - or can even do html!. Keywords to search for (with the latter vendor) are SDW; or in general 'in-line' support. At the very extreme end - consider a POS application (or perhaps even http://www.checkoutapp.com/) with just a cash-drawer, a printer and no till at all. These are generally 'unlocked' easily and a lot of have a simple printerport connection to which you can send an 'esc' 'O' command -- akin to the old EPSON FX-80 era world. Dw.