What is the correct way to close roll-down Ortlieb panniers? What is the correct way to close Ortlieb Front Roller or Back Roller panniers?

There's a black plastic piece of plastic near the opening on the bag that is facing back if it is opened and unrolled that suggests to me that there is a correct direction. Should I roll them toward the back of the bag so the tab is covered with the very first roll or toward the front? Does it matter?
If you rolled it to the front it would not look like that picture.  Yes you roll it to the back.  I have some Front Roller - not making this up.