Books have been exempted from this policy on Amazon.de's site in Germany and this is clearly stated in Amazons' Terms for their sellers...
Are the conditions for price parity for all items that I offer on Amazon EU platform?
The conditions for price parity are valid for all items that you offer on one of Amazon EU sales platforms. The price parity does not apply to the supply of books on Amazon.de. Other parity requirements (e.g. regarding customer service and return and refund policies apply), however, even for that product category. For sales of books that fall under the French law on fixed book prices, the terms and conditions apply to price parity too, but of course these products at the item prices to fixed prices to take account of the book trade. [sic]
[The auto-translation is a little muddled at the end but the main sentence is clear.]
Source: Sheppards Confidential Newsletter No. 163
Original German link: http://www.amazon.de/gp/help/customer/display.html?nodeId=200458420#all