the guys working there are also earning on theirn own effort. isnt it their right who they worship? as long as it doesnt interefere with the business or physically hurt someone?
@MastanKhan have you considered giving a specific time as their prayer time and in return they could assure the business will not be affected by their religious duties?
a few months back a bunch of muslims asked for "prayer time" at an establishment. the establishment promptly said - rules are same for everyone - do it in your break time and breaktime is same for all employees. what they do in their break time is no ones business (as long as it doesnt affect anyone or the work place).
you are in a similar situation here. But being a small business (I am guessing), you have the authority to frame the rules.