BY law in NJ, your landlord should have been doing one of the two, paying you annual interest or deducting it from your rent. (The amount equal to the interest due for the previous year)
The law requires landlords who rent fewer than 10 apartments to place security deposits in bank accounts that pay at least the regular rate of interest. The law no longer allows the landlord to keep any amount to cover his or her administrative expenses.
The law now requires that the interest earned on the deposit must either be paid to you in cash every year or subtracted from the amount of rent you owe on the renewal or the anniversary of the lease. This must be done either when your lease is to be renewed, or on January 31 each year. (But the landlord must give you a written notice that he or she will be paying you on January 31 of each year instead of the date your lease is renewed.)
If this has not been done, then you have some options, but you will ave to consult a real estate attorney for the proper answers and may end up costing you more then your security deposit. If your landlord has an attorney already, he may just tell you to sue him and keep your deposit until you sue and try to get it back at more of an expense. if you shoot for the interest.. ( sorry, just being realistic here)
So your interest is probably about .. $46.75 for the 6 years... if you have not been paid annually. if you have been paid annually.. then it is about 35.00
go to this site for exactly the calculator you want.