Hope this helps, the singer of Rammstein seems to roll every letter in the alphabet lol.
Edit: Also when i roll my R the tip of my tongue is nowhere near the roof of my mouth.
I just lift the back of my tongue, the tip touches my front teeth.
Can you do the hissing x sound like in spanish pronounciation of Mexico? (CH in german)
The point you're looking for is between that and Arabian broad CH sound
(a persian joke says to learn arabian you have to put a raisin down your throat as far as possible and cough it up again, see Achmed the dead terrorist)
Somewhere between Mexico and Achmed something in your throat starts to vibrate.
That should be a RRRolling R.
Edit2: You also have to experiment with the volume of exhalation.