Usually airlines will issue a credit if you call, but it will be in the form of a voucher to be used on another purchase and it will be for each traveler, so you would get 5 x $10 vouchers, one for each person and only the person named on the ticket can use them in the future, you can not combine them to make one $50 discount.
Best bet would be to call and see what they say. Some airlines now charge for this as well so you would not get anything back but not sure on JetBlue. If it's $69 each way you may save though since that's $20 per ticket cheaper.