How do the "pick and pack orders" fees work?

How do the bulk orders work?

For the pick and pack fees for a Bookmobile drop ship, an example is:
You upload one address that one book needs to be sent to:
One book to one address would be $2.50 plus postage.
You upload one address for two of the same book/title to be sent to:
Two of the same books/title to one address would be $2.50 plus $0.50 plus postage.
You upload two addresses and one book needs to be sent to each address:
One book each to two addresses would be $2.50 plus postage plus $2.50 plus postage.
Then for a bulk order, if you have 30 books per carton, you'd need to send a full carton of books (so 30 copies of one title) to one address to get the $8.00 plus postage cost.