If she doesn't go to the bounce house..... doesn't that affect the whole family? So, I would say that's not an appropriate punishment. In my opinion grounding should be a punishment that only impacts the one being grounded.
However, for what it's worth, I don't use grounding, per say, and my daughter is 12. I use more discipline... which means I give her clear explanations of what kind of behavior I want to see.... then if she makes a choice to do something else we talk about what she did.... what's the consequence and how she can fix it. Then she fixes it and we move on. there isn't PUNISHMENT for that.... because what I really want is for her to learn how to behave appropriately for the situation and to be able to apply behaviors to a similar, but unrelated, situation next time.
That's not to say there are never consequences for her. There certainly are. But I'm not about to "ground her" because she gave me attitude. Instead I call her out on the attitude, figure out what the REAL issue is, she takes steps to correct it and we move on. Sometimes that means she doesn't get to watch her TV show.... because we had to re-do homework AND talk about the correct tone of voice to use when you're frustrated.... but it was more effective than just "you can't watch TV tonight because I don't like what you did". She learns a different lesson, you know?
I also think if you are grounding a 4.5 year old for not listening you are going to have hell on your hands by the time she is 8.... and you are going to have to ramp up your punishments so severely in order for them to be impactful that I'm not sure I would want to live in your house. Punishment is supposed to be something that gets taken away that they care about. once you start taking everything away..... she will learn not to care about stuff because she knows it will just get taken away. So you're losing your currency early.
If your 4.5 year old is not listening.... get her attention. Give her 1 thing to do and then do it with her - let her know that nothing else happens until she completes her task and then praise her when she does it correctly. Be consistent. Talk WITH her instead of AT her. Usually those techniques are much more successful than punishment.