Im from Germany and have received packages from the US in the past.
Put the value on the paper lower than 22 eur as Ischeraid said. But not too low. It you only state 5Eur it might look equally suspect. I would recommend reasonable steps which they also can be found in stores. I.e. 14,99USD. Important to mention it in USD. If you put the value in EUR it will also look suspicious when the package comes from the US.
Stil, there is a good chance that they hold it back QualityMechKeyboards. Especially when it is a big package, like for a whole keyboard. In this case they will ask you to come to their premises and open the package there. You also need to present the invoice. They do this in a letter which they send to your home address.
I can give you a few more hints on that if you like, but for that I need to know, did you bought something from a professional seller where you cannot influence the price in the invoice, or from a "normal" person?
And what kind of item is it?