Even better: Make it an employee discount of 50% off at Whole Foods for all Amazon employees, up to some monthly limit. If structured this way, would it even be taxable at all? I'm not aware of employee discounts being taxed.
Concrete example: Company sells widgets for $12, of which $2 is profit. Then as long as the employee price is at least $10 there are no tax implications for the employees. If it were $9 they would owe tax on $1 per widget bought, etc.
That said, some companies will pay the relevant taxes for you, or at least try to by guessing at your marginal rate...