100% Legal Pre Teens How Can I Offer Pre-paid Gas Cards To My Employees As A "benefit"?

How can I offer pre-paid gas cards to my employees as a "benefit"? - 100% legal pre teens

I propose $ 100 prepaid gas cards to my employees every month and the tax structure as an achievement.
I pay less than the employer and the gas card to get "before" tax dollars.

In the end, a gas card for $ 100 instead of cash compensation, the workers would receive a $ 120 - $ 135 U.S. dollars after taxes.

Any legal ideas?