You can edit the POI names, but I don't think that's what you are looking for, as there is probably no installed file of just supermarkets.

If you were to obtain a POI file of supermarkets, you could install that and have a separate category. There are POI files for various chains here

http://www.gps-data-team.com/poi/uni...ates/shopping/

but I don't know of anybody who makes one of all of them (not saying it's not out there, just that I have not seen it). However, the POI editor site below will allow you to merge different poi files into one set so you can combine multiple files.

Install information is here

http://www.poieditor.com/articles/ho...ois_on_tomtom/