Correct me if I'm wrong, but I don't believe that you have to pay taxes on your job because busking isn't technically a profession, it is however a way to work for tips. Since tips are inconsistent, there is no way to claim an amout of payment. Again too, it isn't a salary, you are publicly performing and people tip you.
BOY are you ever WRONG! DokGonzo, when you file you have to file your quarterly taxes with a payment. I just put down a number and claim "tips" and pay on that. Truthfully what I put down and the "real world" may not be the same, but I have never been questioned in several years of doing it this way.
A word of caution. Yes I have 2 sets of books, one actual income and the other my "tax" income. Keep the tax income reasonable according to your expenses and deductions. i.e. tax income of $12,000 but you just bought a new Cadilac. Makes them wonder.