Berlin has introduced a new Hotel Tax of 5%, aimed at tourists. Checking in to a hotel last night I was asked this question, but luckily had seen the poster about the new tax. Answering ‘Business’ solicits are form you have to fill in with details of your employer, but it does save the 5% tax.
You can read a report about it here,but in fact it came in on 1 January 2014.
The self-attestation form can be found here.
More information, provided by the Radisson is here