What happens if the fine is less than the cost of the offense?

Firms opt for the fine:

The relentlessly rising cost of health insurance is prompting some small Massachusetts companies to drop coverage for their workers and encourage them to sign up for state-subsidized care instead, a trend that, some analysts say, could eventually weigh heavily on the state’s already-stressed budget. ...

Additionally, company owners say, it has become far cheaper to pay the state penalty for not covering their workers — roughly $295 annually per employee — than to pay thousands more in premiums.