Point of sale Software

Some body can tell me if I can use linux in my cash register machine (Toshiba A10)?!

I’m guessing YES, as this page:
states that redhat 7.2 is a “supported” OS

and if you google it (search term = Toshiba ST-A10 Linux):
you get a fair few returns, including pdf’s about a -

suse 9.3 driver pack.
SuSE9.3 Linux TTEC Driver Setup Guide for ST-A10.pdf

and the manual mentions suse 9.3 too

Then you would probably need to look into Linux point of sale software… this may be a good place to start:
Top 10 Point of Sale (POS) Software in Linux