As far as I'm concerned, no minigame needs to be 100% complete (when there's such a limit) for you to get 100% at the game. At least, from what I remember from the guide I use. Most of the minigames are completely opticional and there's no such thing such as 100% complete minigame, or if you do need to deal with them and they have a limit, you never need to go all the way if you don't want. On top of that, the majority of the minigames is a one time thing only, like the massage one (and you still get a better item by failing once)