Hello, I am a web development pro and I serve on a webmaster and consultant level for a variety of osCommerce, creLoaded, Joomla/Virtuemart and CubeCart stores. Our store offers a variety of modules that we have built for shipping, payment, reporting, etc... We also have many other modules that haven't been packaged up yet. Needless to say I should be able to fix the problem you are facing easily. It
seems like the others here are bidding on an fulla integration while your store is only in need of a minor tweak somewhere.
Much of my prior work has been done in conjunction with my colleague through the username eastcoastdev which is why I have little if any feedback on this name.
Let me know if you have any questions. Hope to talk to you soon.
Best regards,
Jeremy