Newegg sets flat rates on shipping per item for most people.
The exception is that if someone notices that you're doing a large enough volume of business ($20k in a month, maybe?), they'll put a "reduce shipping price" flag on your account for a while.
I've received as much as 3/4 of a UPS truck full of stuff from Newegg and I had to pay full shipping price on every box in that truck.
And yes, they do put in new warehouses from time to time. I know my stuff comes from New Jersey, Tennessee or California.