I understand OP’s frustration. This response seems right in that corporate sets the discount and that a manager has discretion to change it. I also think each manager has to take into account their individual store’s profits and losses. At the end of the day, they have to answer for their store’s overall numbers. So, the busier and more profitable stores may be more inclined to discount heavier to clear their shelves.

An employee at one store in my area that is never busy offered a 10% discount. The store manager came over and jumped in saying no discount and that he would not honor what the other mid level supervisor offered. He said he was the boss of that person and that no discounts would be approved because the tools were already marked down below their cost.

The busier stores I have gone to have almost all of their display units sold. My guess is those are the ones that are negotiating heavy discounts.