Tennessee is a "right to work" state, which generally means that an employer can hire and fire for any reason or no reason at all, so long as they don't discriminate against any employee. Also, they cannot fire to punish an employee for reporting violations of the law. There is a lot of information available from
LexisNexis(TM) CD
I'd suggest you read that page in its entirety, with specific attention to section h, which should provide an answer to your question specifically. Other information is available here:
TN Department of Labor & Workforce Development.
Nothing in the above message is legal advice, nor should it be construed to be legal advice. I am not a lawyer. Any requests for legal advice should be directed to a Bar certified lawyer.