Tipping is not usually included in restaurant charges.  Typical is anywhere around 15% - similar to what you might tip in the US. A little more for great service, a little less for indifferent service. Sometimes resorts (such as Robert's Grove and Turtle Inn) do add a gratuity or "service charge" on to meals and even tours, so it's a good idea check your receipts and ask if it is unclear.

Other places to tip are similar to in the US, meaning anyone working in a service industry or someone that goes out of their way for you.  One place to keep in mind is dive masters, it is surprising that more people do not tip here. Anything from 10-20% or $5/tank seems appropriate.