There is now a new, clearer way to allow members to access their invoices, payments, and billing history! It's called "My Billing Info" and when enabled, shows up in the left Info Hub navigation options and moves everything from the previous Billing tab to an easier to understand section of its own.
To enable, go to Setup -> Finance -> General Settings and scroll to the bottom of the page. Find the Info Hub Finance Settings and enable "Use the new My Billing Info tab".
Once enabled, your Info Hub should display a "My Billing Info" link in the left navigation menu: