They are probably just passing along the cost of compliance to you.
Since I process through my POS, I have to add some firewall thing that creates a private network that will allow my POS support to continue to remotely access my computers. On top of that, I have to add approved Anti-virus software to each of my stations since they can conceivable access the internet.
Approved Firewall: $800 - $1,100 per store.
Approved Anti-virus software: $15.00 per terminal per year.
The ability to process credit cards for the privilege of forking over 3.5% of sales: PRICELESS!