The choice to "charge sales tax," is not yours to make. The state has their rules, and each county may have their own rider on the state sales tax. The collection is done by a state agency. Undoubtedly, you need to apply for a license to do the collections. As stated above, you never "charge" sales tax, you only are collecting it on behalf of the state (uncompensated, I might add). It is your responsibility to make the collection and then remit to the state as required (e.g. monthly, quarterly, or ???). You will get all the information on where to remit, and the procedure to remit, when you get the license. In PA, all this is done electronically -- not even a choice of doing it by paper.
Getting your sales tax collections in order is on the same level as insurance, licenses, and other things you mentioned. It is all part of operating a successful business.