The European Union countries of Germany and France have a value-added tax (VAT). This is a national sales tax that is built into the prices of goods and services rather than being added at the cash register. The current VAT rate in Germany is 19%; in France, it is 20%.
When you're a tourist from a non-EU country, you may be able to claim a refund of the VAT you paid on your purchases. You can do this using the store's refund affiliate, which can be identified by a decal such as "Tax Free Shopping" or "Premier Tax Free" in the store window.
A participating store gives you a "tax-free shopping cheque." You must present this cheque to customs and show them all the goods for which you are claiming the refund before you clear airport security as you leave the EU. You then take your stamped cheques to the refund service's airport desk for an immediate refund or mail them to the refund service's nearest office after you get home. You can have refunds credited to your Visa, MasterCard, or other credit card in your own currency.
You don't get to decide what service you want to use, the retailer does – so you'll need to process each "tax-free shopping cheque" with the company indicated on the cheque. You don't get the entire amount on the cheque, either – the service through which you process your cheque gets to keep a portion of it.