Kelly, Yes you should tip the taxi driver -- around 15 %. If they help you carry your groceries, you may want to give them extra.

we also have a senior/disables services even in my small town that will take you to grocery stores, Wal mart, doctors appointments, etc. It is pretty cheap.

I cannot imagine giving up my car and license. That will be a really tough day. I do worry that you may be isolating yourself too much.