Many of the costs can be/are negotiable.  With that said,  there are also fees which can be "customary" depending on geographical areas.

The list below is a somewhat traditional split/distribution of fees.

SELLER COSTS/EXPENSES:

Payoff all existing loans: current mortgages, loans, lines of credit. Any loans against the property.

Interest in arrears: plan on deducting approximately 1 months payment of interest.  Although this is truly NOT a closing cost/expense the last months payment will normally be a deduction.  Remember when you bought and a lived in your new home without making a payment for a month?  This is the time to repay that interest for the first 30 days of home-ownership.

Real estate sales commission: normally paid by the seller, unless the buyer has individual representation including compensation.  Some buyers choose to pay their own agent who also negotiates on their behalf.  

Policy of title insurance: this is one of those items that can vary depending on the custom in your immediate area.  It insures the buyer, that when you as a seller depart you leave no "excess baggage".

Escrow fee:  Normally split down the middle between the buyer the seller each paying half.

Home warranty policy: an insurance policy for 1 year after closing, helps to eliminate some of the fear of buying a re-sale home.  Most policies cover major appliances and components of a home.  Buyers normally pay the service call fee of around $40-$50.

Liens: any other obligations, or judgments, whether personal or real which are levied against the property or seller.  This could also include personal IRS liens, over-due child support, that old collection for a medical bill....etc.

Pest control clearance: termite inspection and clearance which includes any corrective work, fumigations or local treatment. 

Transfer tax or fees:  some states, counties and cities have independent transfer fees/taxes.  Most depend upon the total sales price.  Check with a local Realtor in your immediate area.

Homeowner's Association document fee/transfer fee:  Most homeowner's associations charge a transfer fee and additional fees for providing updated financial reports. As a home seller you may save money by providing your buyer with your own copies.  One caveat; be sure you have the most updated documents.

Notary fees: Notaries normally charge a fee based on the number of signatures notarized.  Most likely about $20 for two signatures on a grant deed.

Fix-up/repair costs: It's not uncommon for a buyer to make repair requests based on the physical property inspection.  Depending on the wording in your contract, you may or may not be responsible for property repairs.