As someone who has every single piece of K-ON! music released, I've decided to artist tag them by whoever does dominant vocals (meaning not support vocals that appear on the instrumental version) in the song. So for example, the rock version of the Sakuragaoka anthem is credited to all five of them, while Tsubasa wo Kudasai is credited to the four original members. Honey Sweet Tea Time is credited only to Kotobuki Minako because Toyosaki Aki's vocals there are obviously on the off-vocal track even though that hasn't been released to my knowledge (since she's doing support vocals).
The E Ds are all credited to Hikasa Youko, the O Ps to Toyosaki Aki, and songs like Watashi no Koi wa Hotchikiss are credited to both Hikasa Youko and Toyosaki Aki.
nishishishi~ Nii-nii no baka... .__.I credit fictional bands with the music they write. For example, I have music by Taranchula and sloshy on my computer. In the case of K-On!, I would credit it to "Afternoon Tea Time" or whatever the name is in Japanese.

Sorry if there's a topic for this or something directly related already, but I didn't see anything recent so I figured I may as well make one.
Feel free to talk about anime music in general (...or have this moved to the Music subforum; I really wasn't sure. >_>), but I have a specific query first:
- To whom should anime music be credited as the artist? I'm not talking about stuff like Full Metal Alchemist, where the credit is obvious, but rather Haruhi, Lucky Star, and K-ON, where the singers are also the seiyuu (or rather, the seiyuu are also the singers. :/)
I've already got Haruhi & Lucky Star stuff on my computer - the artists being credited are the seiyuu; Aya Hirano, etc. - but K-ON is proving to be a bit more awkward. When crediting any song, I much prefer to either name the singer/s or band (the band being preferable) but in this case the band is fictional and the singers are varied, despite being the same group.
So yeah. I'm wanting a standardized way to attribute artists of anime music; any suggestions?