Unemployment dipped two-tenths of a percentage point to 5.4 percent in September with most new jobs in government employment and other services categories, the government said Friday.

In the next-to-last employment report before the presidential election, the Labor Department said the economy created 255,000 non-farm payroll jobs last month, down substantially from the 340,000-per-month rate of job creation in the first half of this year.Total employment, according to the Bureau of Labor Statistics' monthly survey of business establishments, was 106.7 million in September.

More than 100,000 of the new jobs last month - nearly 40 percent - were in state and local government. That reflected "a stronger than usual expansion in public school jobs at the beginning of the new school year," said Dr. Janet Norwood, the bureau commissioner.

Private sector employment increased by 140,000 jobs last month, down sharply from the 300,000 per month average in the first seven months of 1988, the department said. In August and September, private sector job creation has averaged 120,000.

Factory and mining jobs fell slightly last month while jobs in the construction industry remained steady.

The unemployment report is adjusted for seasonal variations.

The 5.4 percent jobless rate last month was the lowest since a 5.3 percent rate in June.