Big retail stores, hotels, restaurants and other companies with lots of low-wage and part-time workers are among the main beneficiaries of the Obama administration's latest tweak to health care rules. Companies with 100 or more workers will be able to avoid the biggest of two potential employer penalties in the Affordable Care Act by offering coverage to 70 percent of their full-timers. That target is considerably easier to hit than the administration's previous requirement of 95 percent, but the wiggle room is only good for next year.