Large ticket items like rent and (especially) condo/hoa fees you want 100% off the funds to flow through to the budget.

I encourage you to participate in your board. You'll get a sense of the ramifications of 3% haircut off the budget.

Commercial stores and such have higher profit margins (and batching deals with the cc processors) such that they pay less in fees and have more "room" to eat the cost as a way of getting you in the door.