In France, service is always included in the price.Your bill may mention it or not but it is included.
Sometimes you ‘ll see for example « Service compris 10% » ; it may go up to 20% in the very elegant or gastronomic restaurants in which there are more employees than customers!
The French usually tip only if they have appreciated the moment they have spent in the bar or the restaurant, or if the waiter was especially pleasant. Personally I prefer to leave some coins on the table rather than to round up the amount of the bill paid with credit card. Doing this, I’m certain that it will go to the waitress.
For example in a restaurant, if I’ll leave tip 2 € for a meal for two if think the service was nice and the meal good value. Or in a café I’ll tip some yellow coins ( cents of euro) If I especially enjoy my cup of Champagne.
If you want to know more about France and French: please come and stay in our guest house in Reims . We are always glad to exchange with our guests, B&B is the way to meet a country and its inhabitants.