Can my employer refuse to pay me during training period if I quit.

I started a job today at a restaurant. The owner offered me a job at 9 dollars an hour two days ago, when I went to work I had to sign an agreement to work at 7.25 an hour for 90 days (probationary period), during this time the owner will withhold 100% of my pay. The agreement also states that If for any reason I am not on the payroll at the end of this period the owner will not pay me any wages what so ever. I am already looking for another job because this is plainly not what I signed up for. I'm assuming every hour I work for him will be lost but I was wondering if this was a legal practice.