There are many things which comprise the Closing Costs:
The Prepaid Taxes are a big thing, or can be; they can be 1/12 of the Old Tax assessment, up to 1/2 of that amount.
There would be Title Fees, Insurance fees, Notary fees.
You will find that the difference between the highest and the lowest as far as their own fees are concerned, is maybe a few hundred dollars.
The Bank doesn't vary or determine most of the charges.