How do I make sure that Canonical get affiliate benefits when I buy from amazon?

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http://askubuntu.com – Ubuntu 12.10 has a new feature to search and buy from Amazon, either from the Dash, or from a unity WebApp. This is quite controversial, but for my part, I quite ok with it. So when I buy something from Amazon (which I did before, and I'll do tomorow), I'd like to make sure the affiliate revenue are really given to Ubuntu/Canonical: I would have bought anyway, so financing my prefered OS by doing so makes sense to me. But the question is : how does it work, and how can I know my order get accounted to Ubuntu/Canonical affiliate program ? What if I navigate the amazon site before I buy ? What (HowTos)