The complaint alleges that thousands of Dollar General stores "have taken advantage of vulnerable shoppers by extracting millions of dollars in unlawful overcharges with insufficient safeguards to prevent the practice." It also says the company has received "tens of thousands" of consumer complaints about being charged more than advertised prices but has not implemented policies to address the problem.
Shares of Dollar General fell about 4% after the lawsuit was announced.
The states joining the FTC in the suit are Alabama, Arizona, Arkansas, California, Connecticut, Florida, Illinois, Iowa, Kansas, Louisiana, Michigan, Mississippi, Nebraska, New Jersey, North Carolina, Ohio, Oklahoma, Tennessee, Utah and Wisconsin.
"Dollar General has betrayed the trust of millions of American consumers and imposed significant financial harm on communities and consumers who are already struggling to make their paychecks last," said Christopher Mufarrige, director of the FTC's Bureau of Consumer Protection.
Dollar General did not respond to a request for comment.
The lawsuit comes as shoppers seek discounts amid elevated food and gas prices, and as officials across the political spectrum aim to demonstrate efforts to protect consumers from high costs ahead of next week's midterm elections.