Oh you can accept them alright. Just recharge the extra tax to the customer, if they're from MA. You don't even need to worry about if it applies to that particular invoice or not - Just add it in any case.
I wouldn't suggest that you keep the funds for your self. You could just pay it through in any case - I'm sure the MA tax department wouldn't mind. And I would also assume that to be a lawful practise.
The point is that you make it clear why your customers are being charged extra. It's then up to them to contact their local representatives and ask them to change the law. If you're not based in MA, it's not really your problem. Sucks for businesses in MA of course.