It is certainly legal to pay servers either $25 or $15 per hour (it's also generous): the only obligation is to pay an amount equal to or greater than minimum wage ($7.25 per hour), which this certainly is. It's also legal to vary employer wages by the day or the event, as long as the change is made prior to when the employees do the work (i.e. before you start serving).As for the prior way of paying you: while it's possible the employer may have technically violated some laws, depending on exactly what he called the charge, how he reported it, etc., from an employee point of view, as long as with what you were paid ($2.15 per hour) and what you received as your share of the gratuity, you were received an amount equal to or greater than minimum wage, you were treated legally. So, say an event was 4 hours; minimum wage for 4 hours would be $29.00; if between wage and gratuity, you received at least $29.00, the employer met his obligations to you.