Securing systems is on every merchants mind and is more than just anti-virus and keeping up to date on the latest patches. Management should be concerned about many other security aspects, especially browsing the Internet and blocking sites that are not business related, since malicious software is often found on common social and entertainment related websites.
Many store level machines have Internet access and are allowed unrestricted browsing. This raises concern because all viruses cannot be detected with basic anti-virus. Limiting Internet access by minimizing websites allowed through white listing will most certainly reduce the risk level at stores.
So, a suggestion would be to restrict your employees to business purpose websites only. Some of the management headaches can be relieved right there.