The best way to calculate closing costs is simply go to a lender, real estate agent or title company -- they are usually happy to do the math for a potential customer. In general, closing costs in Maryland are about 5 percent to 6 percent of the purchase price.For residential property in Maryland, the tax is actually levied on 40 percent of the market value.). For a $100,000 house in the city, 13 months of taxes would run about $2,535. In the county, a house of the same price would require about $1,300.