Retail sales, held back by sluggish business at car dealerships and department stores, edged up a slim 0.1 percent in March after posting a sharp decline during the previous month, the government reports.

The Commerce Department said sales rose to a seasonally adjusted $139.42 billion last month after falling 0.6 percent in February and jumping 0.6 percent in January. The figures are not adjusted to exclude the effects of rising prices.For the third straight month, overall sales in March were held down by a decline in spending on autos, which account for almost one-fourth of the retail total. Car sales were down 0.1 percent in March after declining 2.5 percent in February and 1.9 percent in January.

It was the first time auto sales have declined for three straight months since July through September 1984, when the decreases were more pronounced.

Carmakers in recent weeks have launched a new round of incentive programs in hopes of luring customers back to showrooms during the prime spring selling season despite higher interest rates for loans.

Excluding the automotive category, retail sales last month still were up just 0.2 percent after holding virtually even during February and rising 1.4 percent in January.

Retail spending accounts for about one-third of overall economic activity and is closely watched as a measure of the economy's health. Many analysts are expecting an economic slowdown this year in response to an ongoing campaign by the Federal Reserve Board to push up interest rates and thus dampen demand and restrain inflation.

In the key category of department and other general merchandise stores, sales fell 1.2 percent in March to $15.6 billion after declining 1.5 percent in February.

In a separate report earlier this month, the nation's big retailers reported mixed March results, with giant Sears, Roebuck and Co. reporting strong sales under its new competitive pricing policy while other chains were less pleased with last month's showing.

Overall, sales of durable goods, "big ticket" items expected to last three or more years, were down 0.2 percent last month after plunging 1.7 percent in February.

Sales of non-durable goods, meanwhile, rose 0.3 percent in March after climbing 0.2 percent during the previous month.

Among the categories of goods to report sales increases last month were: food and grocery stores, up 0.2 percent; gasoline service stations, up 0.5 percent; and bars and restaurants, up 0.5 percent.

Categories posting declines included building and hardware stores, down 1.9 percent; furniture stores, down 0.2 percent; clothing and accessory stores, down 0.4 percent; and drug stores, down 0.2 percent.

For the first three months of the year, overall retail sales were up 5.7 percent from the same period in 1988.