Asking taxi from airport to stop at Comercial

In March we came in and rented an SUV from airport to Playa La Madera for six of us. Our taxi driver didn't speak English so I asked the gentleman that gives them your ticket if I tipped him extra could he stop at Comercial for us to get some groceries. I told him I would try to be quick as I know they want to get back to the airport for more fares. I gave him 200 extra peso. Was this ok to do? Was it to little of a tip? It probably took us 30 minutes (not as quick as I hoped) to get through the store. I don't have any problem giving them more then that as it saves me having to go back on our first morning and just want to be sure they are getting a fare rate for waiting. We are coming back in September and I would like to do the same thing again although it will just be two of us this time so I will actually probably be faster then trying to herd 'cats' (family) through the store.

Thanks in advance.