yep - there are breaks (by price) in the "marketable order size" that can influence the bid and ask.
MM's will often line up a tick above the next order size break. If the stock gets there, they want in on the action, or at least an alert that something is happening, but they aren't going to work to get it there...
If I could afford to buy all of them, I would not need to buy any of them and I sure wouldn't be spending time on the message boards!