If you catch someone abusing your equipment or property, they should be let go.
The 'reward' payment for doing what any employee should be doing anyway is like a foreign concept. As an owner, you will spend more minutes throughout the day micromanaging to 'enforce' this policy.
For 4 employees, that would be an extra 560 a week
I would look into other ways to make employees feel valued, team building exercises, motivation techniques, etc that don't always have to be about money.