Hi,
just to add to this. Generally, password synchronization is a bad idea. It's error prone and should be replaced by SSO. As mentioned by Jim there are solutions that target retail environment where many people share the same client. I would look there first but I understand that it will require some investment.
If you decide to go password synchronization then SAP IdM supports this. The way how this works is that it encrypts password (the first problem here) and pushes it to all backend systems relevant to a user. Again, this will require some investment if you don't have IdM already in place.
Based on my presonal experience with retail environment the best solution is using both. In retail there is usually high turnover for employees so you really want to avoid using any IT resources in this process. Hence IdM can provision user details to all required systems based on data coming from HR system. SSO is used for authentication to the systems.
Cheers