Well, I like your thinking.

You have a clean system in mind and it would give everyone (do you have an age in mind for this to start, or does an individual request this whenever they are ready?) a fair chance of expressing themselves via the Percentum method.

Not sure what the benefit would be to make contributions in self-chosen percentages to local, state and federal level. Should they not all be seen as 100% each by themselves? They are three levels of governments right above our heads. Or perhaps that is what you mean?

Naturally, I see bears on the roadway. How to implement this. Have you thought about ways to present this to others? I have a hard time wrapping my head around the way it would function for let's say a community with 5,000 people. Can you come up with an example how they would use it to express themselves for that local city with 5,000 participating Percentum voters, and then how it would work for the other governmental levels? It does not need to be accurate in political details, but I would like to see the system itself in an example to get a grip on how it functions.