All service charges and taxes at restaurants and hotels are included in the tour price. Tipping, although not necessary, is at own discretion. The general rule is that you tip if you are satisfied with a service, for example in a restaurant. In the Scandinavian countries this is often done by rounding up the bill (about 5 to max. 10% of the total bill).
You are free to tip a guide that you were satisfied with. There is no fixed rule or expectation for how much to give. For our guided tours, you can roughly calculate with EUR 10 per day of the tour for the tour escort and about half for the driver if you feel like tipping them.
Here you can find some more information on tipping etiquette in different countries.