Yes, switched to plastic to save the trees. Montgomery County, MD requires stores to charge $0.05 per bag.
Some concern has been expressed of the reuse of bags in that harmful bacteria is retained and deposited on raw foods.
And that's for plastic or paper bags. Even restaurants have to charge for plastic bags, though they're exempted from the charge for paper bags.
When they proposed this, they were trying to sell it as a "fee", though I rightly pointed out it was an excise tax, not a fee, since the government wasn't providing any form of service. Of course, now that it's passed and implemented, they have no problem calling it a tax.
As a former grocery store worker (ie. stock-boy, bagger, floor mopper, general do-whatever-needs-doin') I can say for hauling groceries I'd rather go back to paper. Plastics are a pain in the neck (or lower) to get open, rip easily, and their one-size-fits-all approach stinks. We used to carry 3 sizes of paper bags and they had a lot of uses too.