I build and maintain Cash Register Systems powered by
L-anePOS.
L-anePOS is an integrated, multiuser point-of-sale (with some accounting) program for
computer systems running a Unix-like OS (most commonly Linux). It allows
businesses to track inventory, sales, customers, and other accounting tasks
in a single or multi register setup. L-anePOS is designed for both retail
stores and restaurants. Any back office computer running X11 (or an
intermediary) can access the system for reporting or modification.
Here you can check the
Stocks
and
Products
of Electrical Engineering Study Association
Thor. Where L-anePOS has been used since August
2002. (these are just simple scripts that spit out some tables from the L-anePOS database.)