The 'F5' button located on the toolbar at the top of the page can be selected by using the corresponding F5 key on the keyboard or by using a mouse click.

F5 - PrevPg (Previous Page)

When this button appears in the toolbar, you can select F5 to go to the previous page of the record.

Example

When you are in a record as below on the page titled "Order History", if you select the F5 - Prev Page key you will be taken to the previous tab along in the record, titled "Sales History" as in screen two.