Frankly, if you didn't tell your employer about your religious observances when you were hired and its now become an issue you're at fault for not letting them know.  You do have legal rights to force your employer to make an accommodation if there are a sufficient number of employees to come under the federal labor and civil rights laws.  Doing so will get you your rights but it will also antagonize your employer or manager.  I get the sense you're a pain in the ass employee and unless you're a high performer your employer or manager will be looking to develop a record of poor performance so they can document legitimate reasons for letting you go.  If the business is not doing well you WILL be one of the first to be laid off.