Quick steps on how to redirect back to your magento store upon a successful purchase. Unfortunately, you can only redirect to one page.
- Sign into Paypal account
- Click directly on Profile -> Website Payment Preferences
- Change Auto Return to on.
- Fill Return URL to http://www.mymagentositregoeshere.com/checkout/onepage/success/
- Save and then go test it!
After a successful paypal payment the customer will be redirected back to the magento order success page. Hope this helps!