New Redemption Grab Bag now includes an assortment of 500 cards from five (5) different expansion sets. Available at Cactus website.
Yes and no, is the answer. Heavy Taxes does NOT say, "cannot be negated." So, if you prevent it, then it does not work. Also, if you have a card (such as Covenant with Noah or Gamaliels Speech) that negate from OUTSIDE of battle, then you can use that to negate Heavy Taxes as well.
All end the battle abilities effectively have ”cannot be interrupted” status because the ability is used in the battle phase and causes the battle phase to end, and abilities can only be interrupted or negated during the phase in which they are used.
Might be a good topic for a Real Rulings with Redoubter.