Ideally, iggygirl, you'll temper without the aid of a thermometer. It's not hard or mysterious at all and you're better able to cope with variables. Use the thermometer once or twice so you know what you're looking for and then chuck it.
Besides, even if you don't temper very often what do you do when the thermometer breaks (because they inevitably do if they're not already lost, stolen or borrowed)? You can't tell your chef or your client that they can't have the product, so you'll end up tempering by eye/feel anyway.