If you are talking about the built-in POIs, you can add (using MapShare) any shop you like, but all your additions will come under th general "shops" heading and it is unlikely they will get shared to others.
If you are in America, you do get brand specific icons for some POIs, but you will not be able to add more of those to the built-in POIs.
What most of us do is add our OWN user-POI categories. these can be of anything you like, so you can have a category for electronics shops, one for butchers shops, one for whatever you like. you can also have a custom icon on screen for each one.
You can make the category lists yourself or you can download POI files from the internet and install those.
OK, I guess you can add any shops you like and send them via MapShare.
In the UK, the "shops" POI used to be completely useless, because it only had a branches of a little-known Car parts company and rich-person's shop Harrods!
Now however, it has an awful lot more "ordinary " shops, but it's still not much use because there is no sorting into any categories of types of shop.
Often all you get is the shopkeeper's name (such as "Maguires" or "EG Wards" which are within a few hundred yards of me, but I have no idea who they are).
So try to give as much information as possible in your submissions to TomTom.
I think you are from Lithuania judging by your IP address and in Lithuania it seems the main shops listed are the Maxima, Norfa and Iki hypermarkets?
So by all means add any types of shop you like, but I've no real idea of how well MapShare is working on sharing POI submissions.