My personal view on this is:
Successful payments: I create and send them to a 'thank you' page. Customers like to know that everything has gone through ok. Sometimes on this page I will then have a feature that tells them about another site I or my clients may have... for example, someone just purchasing a wedding dress gets taken to a page to say 'Thanks for the payment, your order will be with you....' and by the way... please visit my wedding ***** site at
www......
Cancelled Payments:
I take them back to my home page... you never know... they might spot something else?