We didn't stay on site at DLP, and didn't have any sit down meals either, so we weren't confronted with a tipping opportunity. I don't know what is customary or expected at DLP.
We did spend a week split between the south of France and Paris and they don't tip there like we are used to. I'm used to adding 15% to just about everything (meals, taxi fares, etc.) and that isn't the custom in France.
We stayed with French friends for most of the week. They told us that you usually don't tip. Not for meals, not for bell services, not for much at all. He told us that we should give the driver a couple of Euro on a 70 Euro fare from the airport to Paris. The driver seemed very happy with that.
Our friends explained that in France, people don't want tips as it is a sign that you are better than them, or they are beneath you and serving you. It seems they want to do their job and be paid, but don't want a handout. Or so our friends told us. I trust what actual French residents say a little more than a guidebook.
Actually, when you have a meal and are presented with a bill and pay with a credit card, there is no place to leave a tip even if you wanted too. If tips were expected I'm sure there would be a place on the credit card receipt for them.
That was our experience, but I'm sure others have seen different.