Dear Customer (name blocked for privacy),
Unfortunately, unless an employee is hired and told certain policies will never be established, or the employee works under a written contract that says he/she does not have to do as a new policy establishes, the employee is likely an "employee-at-will." Employers can normally change the hours, terms, and job functions of employees-at-will for any reason or for no reason, as long as the change is just not due to illegal discrimination (race, religion, gender, age, etc.).
If a retail store's corporate office gives store managers the ability to set policies regarding sales quotas or requirements, and such policies are not illegal from the perspective of consumers (not employees), then the manager can set such policies, even if they change the way employees were expected to work. Also, if an employee-at-will cannot work under the new conditions or does not meet the new standards, an employer can elect to dismiss the employee.
PLEASE NOTE: Responses here are for information/education only, NOT legal advice and do not form attorney-client relationship! Only licensed attorneys you hire in your state can provide legal advice.