I'm pretty sure the Apple Store doesn't offer the granularity of customers directing certain payments toward taxes.
If I go to the corner liquor store and I make a $10 purchase that has 9% sales tax, it's not like I can pay $10 on a credit card and pay an additional 90 cents for the sales tax. The merchant sees the transaction as a total of $10.90 and will eventually remit 90 cents to the state's tax board. But it won't be those 90 cents in currency.
Apple will simply require payment via a method accepted as a valid source.
In the same way, if you pay with a $10 bill, no one cares if you earned it from tips, allowance from your mom, or something you picked up off the street. It's still an accepted payment method.
Whether or not you legally acquired it is between you and legal authorities (tax agency, police, etc.) not something Apple really cares about assuming it's valid legal tender.