Generally speaking, an employer may legally do so according to the Nevada Office of the Labor Commissioner. An employer may require a prospective employee to present their OSHA 10 or 30 Hour Course Completion card or proof of training prior to hiring them. In this situation, the costs associated with obtaining this training could lie with the prospective employee.
Since this question again involves labor law, employers should contact one of the two Nevada Offices of the Labor Commissioner (Las Vegas (702) 486-2650 and Carson City (775) 687-4850) for more specific guidance.