In this case, you are probably concerned with sales tax exemption. That is a state issue, so you need to explore the laws in your state.

First - you need to know what you as an entity are exempt from. If set up properly, perhaps in your state you are totally exempt from paying/collecting sales tax. In Texas, we are allowed 2 tax free fundraisers per year. We can have more, but sales tax must be paid.

Second - (unless you are totally exempt) you need to know what is taxable. What are the kinds of things that could be subject to sales tax? If you sell items, like T-shirts - those are likely subject to sales tax. Food can be very complicated. Sometimes if it's made from scratch (spaghetti supper), no tax but if it's simply re-sold (pizza) then tax should be charged.

If you need to pay sales tax, that is no big deal. Thousands of people/businesses do that every year. With something like a PTO, it's probably an annual filling with your state Comptroller or other financial agency.

Guest is correct in that you have no limit on the number of events you run or whether or not they turn a "profit". The definition of "fundraiser" is really internal. You may run an event for the purpose generating major funds. You may run another to break even. Whether or not it "makes money" has no bearing. Whether you call it a "fundraiser" is pretty much up to you. That doesn't generally have a legal connotation.

There aren't any IRS restrictions on number of events. At least not just because you are a PTO. You school may have some restrictions or the sales tax issue might kick in.

The most common misconception about fundraisers people have is that a fundraiser has to make a profit. It is not true. All you have to do is raise funds to have a fundraiser. It can be done as a service. It can be done at cost. A fundraiser can actually loose money and it is still a fundraiser-albeit a bad one.

How my tax exempt fundraisers can you have a year? If there is a community function like a festival where you charge people for tickets to play game and to eat. Is this considered a fund raiser?