The cost of buying almost everything in the District of Columbia will rise today when three new or increased sales taxes go into effect.

The general tax rate on most merchandise other than food, drinks and gasoline will rise from 5 to 6 percent. Imposition of a new 6 percent sales tax on the pump price of gasoline was postponed for five days by court order late yesterday. The sales tax rate on the price of renting hotel and motel rooms will rise from 8 to 10 percent.

For the first time, a sales tax will be applied to candy, confectionery items, chewing gum and soft drinks at an 8 percent rate, except when sold through vending machines where the present 2 percent rate will continue to be absorbed in the retail price for each item.

Information about the new sales taxes is available from the D.C. Department of Finance and Revenue at 727-6152.

Also going into effect today is a new 1 percent transfer tax on the value of real estate that normally will be paid by the seller. This is in addition to the existing 1 percent paid by the buyer.

Information on the transfer tax is available at 727-6477.