I integrated http://saasy.com/ http://saasy.com/. It seems a bit pricey compared to other options but they handle things like charge backs and locale specific

I integrated http://saasy.com/ http://saasy.com/. It seems a bit pricey compared to other options but they handle things like charge backs and locale specific tax. Whether that justifies the higher commission rate is debatable. Some things I didn't like about it: (1) For new / low volume users there's a mandatory telephone number field. (2) Once the transaction is complete it's not possible to automatically redirect back to your site.