Eh, not sure if I would say that. There are a lot of legal rules about how blame is assigned.
https://en.wikipedia.org/wiki/Joint_and_several_liability
https://en.wikipedia.org/wiki/Joint_and_several_liability
If we're talking about tort law, then yes, damages are measured in dollars. And those damages are absolutely subject to rules about how they are split when multiple people are liable.
If we're talking about crimes, then "percent of blame" is nonsensical. There is no percent liability for a crime, you either are guilty or you are not.