Zip code zones are independent of political boundries. For example, the East Hopewell Township building is a Felton address. Some areas of EHT are Airville or New Park with most being Stewartstown. Heck, there are a few addresses in Stewartstown that are in North Hopewell Township and some even have a 235 exchange. Talk about an identity crisis!
In the case of Home Depot, everything on the north side of 851 is Hopewell Township, but a New Freedom zip code. It is the township that matters when it comes to taxes being collected. They go to Hopewell Township. Everything in Stonebridge is in Hopewell. The stuff on the other side like the gas stations and True Value are also New Freedom but they are in Shrewsbury Township.
Hope that answers your question.