Yes, in Roatan, you should plan to tip your food servers, bartenders, spa service providers, cleaning staff, and of course, dive instructors, boat captains. It is not customary to tip in land taxis (called collectivos here) but you might round up when paying. Same for water taxis, though generally these guys are quite personable and go above and beyond to help you in /out of the boat, so you might consider it.
It is customary to tip 10-20% in restaurants based upon the level of service. Some restaurants include tip in your bill and this will usually be listed as "propina" (tip in spanish). For dive instructors and boat captains, the 20% of the fun dive cost or course cost is customary, distributed between the two. Or a general rule of thumb is $5 per tank to each.
How dive shops accept and distribute tips widely varies - and is always a topic of big debate online. First and foremost, do tip your dive team. In Roatan, this is a part of their compensation and is a way to recognize and incentivize those who go the extra mile.
At Sun Divers, you can tip our team directly - or you can add a tip to your final bill. We provide you with a tip card that allows you to allocate a percentage of the total tip to the instructor-divemasters, captains and office staff (not including owners). We keep track of the instructor-divemasters and captains you dive with throughout your trip, so we know how to then allocate their share of the tip. If you do not allocate a percentage, we will split it 45% divemaster, 45% captain and 10% office staff. For courses, we will default to giving 10% to office staff and split the remainder 70/30 to instructors and captains.