Tukad Cepung Waterfall still remains as the best virgin waterfall of Bali. The fact that this spot is not known to a lot of people and still not under the commercial tourist spots, you are not under any obligations to pay anything to enter area. However, since the area is well-maintained by the local villagers and some of them contribute in showing and/or explaining the waterfall to the visitors, it would be kind if you gave a tip so they can continue to maintain this hidden spot.