My employer is taking my overtime hours and carrying them over to the next week in order to avoid paying overtime since business is slow. That isn't right is it? My boss wants us to keep our hours under 40, but since we are a retail store(and sometimes get busy w/ customers) I may get 2 -3 hours over.
Our accountant informed the manager this was illegal? But he just blew her off. Should I file a complaint?

Yes, this is illegal for private employers.
http://www.dol.gov/dol/allcfr/ESA/Title_29/Part_778/29CFR778.104.htm

If the employer won't listen to the accountant, sounds like you may not have a choice but to file a claim for unpaid overtime with the state Dept. of Labor.

Agreed. You might find the following of use.

http://www.dol.gov/esa/whd/regs/compliance/whdfs23.pdf