The general rule is that the closer you are to your root domain, the better. It is said that Google weights subfolders in descending order. For example:
www.xxxxxx.com/card/wow/20-euros 2 .1 /3 /4 /5 5
Basically, that means that your domain gets the highest ranking power for your words, followed by subdomain (if applicable), then position 3, 4, 5, etc.
And as Matt Cutts (of Google) stated (and recommends as a best practice): Google treats the hyphens in the URLs as a word separator, which basically says this:
www.xxxxxx.com/card-wow-20-euros 2 .1 /3 3 3 3
This allows all four words in your URL to obtain the same ranking power for each keyword: card 3, wow 3, 20 3, euros 3 instead of card 3, wow 4, 20 5, euros 5.