Hi David,
Ellzy has given an excellent answer to your question already so there's nothing really to add. Thanks Ellzy for passing on your recent experience with the exam. That's a big help for those about to sit.
As to David's questions:
The exam question will make it clear that it is a charter or private flight and you will then include or exclude the 15% reserve respectively. In real life though, most of us would probably include a 15% variable reserve all the time regardless - even though the CAAP doesn't say we really need one. Like that old saying that Bob quoted: "The only time you can have too much fuel is when you are on fire".
For the beta test written answers, I'll doublecheck but I think the answers for fuel required had a tolerance of +/- 0.5 meaning you could put the exact amount in or round to the nearest litre. In the exam though, it will be all multi-choice and the answers options will be more than 1 litre apart.
Take note of what Bob said about the answer "being closest to...". That's the key.
Again, this is all just exam technique. In real life, your company or flying school fuel policy will guide you e.g. round up to the next 5 litres.
Good luck with your exam mate. Fingers crossed! Not long now
Cheers,
Rich