Is it illegal to ask for money?

Yes and no.

First generally speaking, it's not illegal to go door to door to ask for money. Usually this is accompanied by a service...BUT there is nothing that says you can't just ask for money.

However NEARLY ALL cities, townships, parishes, or what have you require a solicitation permit.

Therefore it is illegal to do so without the permit.

I believe this is a civil issue and not criminal, so if you knock on someones door and they call the police, they may write a ticket (if not just a warning) for not having a permit, but will not take you to jail.

If you do not have a good or service that you are selling...YOU SHOULD MAKE IT KNOWN that you are asking for a voluntary handout, donation, etc... Otherwise it may be misunderstood as an attempt at robbery. At which point criminal charges could be made, if a complaint is filed.