Giant Food Inc., already basking in its successful introduction of computerized checkout systems at all of its outlets, announced today that it is expanding the system to permit segregation of drug items on checkout slips -- providing for simpler customer income tax preparation.

Donald R. Buchanan, Giant's vice president for data processing, also told stockholders at the company's annual meeting that he hoped the system could also be expanded to provide customers with forms to speed the processing of medicare payments.

Buchanan's remarks here, at Giant's major food warehouse, were part of an enthusiastic program presented to about 200 stockholders who attended the meeting,

Israel Cohen, Giant's board chairman, said after the meeting that he expected the company to hit a sales figure of about $1.25 billion in the current fiscal year, up from $1.08 billion last year.

Cohen also said he hoped the opening of a new Giant Food-pharmacy at 7th and O Sts. NW would provide the company with the impetus to expand further in the District.

Many District citizens and government officials have been expressing concern about the limited number of grocery stores available to residents of the city.

"After 7th and O things will start to happen," Cohen said.

In remarks during the meeting, Cohen said the 34,000-square-foot D.C. store, which opens on Oct. 10, will be the first new chain supermarket opened in the city in 11 years.

The store is being built under a joint agreement between Giant, which owns a third of the joint venture corporation, the D.C. Development Corp., which owns about 57 percent and the Shaw Project Area Committee, which owns the remaining 10 percent.

Cohen said the company will open three more stores within the next three months. Two of the stores are in Virginia and the third in Maryland.

The company presentation, which emphasized Giant's efforts at computerization and in consumer affairs, also touched on Giant's national ranking in the nation's retailing sector.

David B. Sykes, senior vice president for finance, using tables prepared by the trade journal, Chain Store Age, said Giant ranked first in the nation in five asset management categories -- including capital investment compared to sales and operating income when compared to sales.

Sykes also told the stockholders that if someone had purchased 100 shares of Giant stock when the company first started offering public shares in 1959 at $16 a piece, the shareholder would have received a 9 percent return on the investment.

"I believe our 9 percent will compare rather favorably with the return on some of your other equities," Sykes said.

"Giant has a balanced mix, good stores, quality products, value, superior service, and people who are both motivated and productive," he said.