Employer has been editing my timecard since March

Long story short, I work at a retail store in Michigan that is open from 10a-6pm. I clock in at 9:55a to count the drawer and open up the store. Very often I am stuck there until after 6pm to help customers and then close the store down. I recently found out that my employee has been editing my timecard to only reflect the hours the store is open and not the actual hours worked so if I actually worked 9:55 to 6:10, that has been edited to only show 10-6. I have never been told not to clock in early or that my timecard was being edited in the first place.

Is this legal for them to do? I looked back through my past timesheets and it’s been happening consistently since March so I have no idea how much time they’ve actually docked from me.