Your employer is mistaken about the EPPA rules saying you had to take the test. The Employee Polygraph Protection Act of 1988 does indeed include an exemption for armored car companies, but that exemption only allows them to polygraph prospective employees. It doesn't allow them to order existing employees to submit to polygraph "testing" in the context of an internal investigation such as that you described.

Your employer violated the EPPA by compelling you and your colleagues to submit to polygraph "testing." I think it would be prudent to at least consult with a lawyer with experience in labor law regarding your situation.

Hello

Three of us took a polygraph for an armored car company. 
We all came out as incomplete. This went on for hours.  We were told the EPPA rules said we had to take the test.  We signed the forms and came back for the test.

On Friday we were called and told we were on suspension for th next week pending further investigation.  All over $175.00 in missing coins. 

Should the three of us get a lawyer or wait and see what happens.  We are only making $22.50 an hour which is not a lot as armored car people are attacked frequently at ATM machines.