iPhone tethering on prepaid SIM?
 

Hello!
I will be staying in Germany for about three months, and I would like to use my factory unlocked iPhone 4 while there.
I am mainly interested in data access, as it would be my main internet connection during my stay. From what I researched online, the best deal seems to be Tchibo - 5GB for 20 euro. Is that still correct?
Also, do any of the prepaid carriers allow native iPhone tethering? I would not mind paying a little extra for that.
Thanks!