There are five endings, but they usually happen in a combined form. So here are all the possibilities I can think of:

1) Bad Ending
2) Normal Ending
3) Sad Ending, Normal Ending
4) Normal Ending, Good Ending
5) Normal Ending, Good Ending, Perfect Ending

Depending on what you do in the game, one of those five will happen. The Normal Ending will always happen (except for with the Bad Ending, but you didn't actually beat the game if you get that). And there are things that you can do to add on to the Normal Ending, that's basically what it is.