Have you tried bungee cords? ;) We had to do that on our pantry door in our rear kitchen... :(
Actually, there is a heavy duty latch here:
cabinet latch Have not seen it in person, but at $10 per each, it must be good. I'm going to try one on our pantry door.
Those magnetic catches are rather weak to start with. We wanted to use them in place of the "standard" ones used like BFL13 has in his link on our new TT. The dealer was going to replace them all for us on doors and drawers but they found they were far too weak so we left them alone. For a small medicine cab. door it should be fine.