It is not expected to tip in Iceland contrary to other countries. Most of the bills already have the gratuity or service charge added into the total and most of the workers make decent wages in Iceland. Even though tipping in Iceland may not be expected, it is still always appreciated, and it is up to your own appreciation of the service received.
During our tours you will not be expected to tip the tour guides. A tour guide makes decent wages and does not rely on gratuities. However, if you wanted to express your appreciation to him or her for an exceptionally interesting excursion. It is not customary to tip the coach driver on a tour for the same reasons but also, it depends on your appreciation of the service provided.