Exactly what I was thinking. One feature you'd have to include though is a way to back out transactions at end of day. A lot of small, independent family run retailers (especially coffee shops, corner stores) have software mods to their cash registers for reversing sales at end of day so they can remove them to avoid paying taxes.
If I was doing this, I would be very leery of accepting an advanced, internet connected POS device into my store rather than my trusty old, hackable offline cash register. It would take a huge increase of sales to overcome the money saved by not paying taxes on a portion of sales.
Or decouple the POS and inventory/catalog systems and have a restricted interface between them. Only the inventory system needs to be indexed for search.
If I was doing this, I would be very leery of accepting an advanced, internet connected POS device into my store rather than my trusty old, hackable offline cash register. It would take a huge increase of sales to overcome the money saved by not paying taxes on a portion of sales.