I killed Tenpenny too. It gave me positive karma when I did it. Bigoted *edited* anyway. I never actually finished the quest though. I ended up getting hooked into the story again and just finished it.
Spoiler:
I sacrificed myself to activate the purifier and bring clean water to the Wasteland. I’m assuming if I dont die you can keep playing like in Oblivion? If not that’s kind of lame if the game doesnt let you continue after the story. Still, I liked my ending.
Now to play again and be an evil *edited*…