At your discretion you might also consider tipping your Tour Leader in appreciation of the efficiency and service you receive.
Although entirely voluntary, tipping is a recognized part of life in this region of the world. Some local staff will look to members of the group for personal recognition of particular services provided. In order to make things easier for you, the Tour Leaders may organise a group's tips kitty and if this is the case, they will account for it throughout the tour. Accordingly, you should allow US$ 35.