The library is chartered as a school district public library and thus exempt from NYS sales tax. Due to a mold issue we ended up having our HVAC contractor rent two humidifiers for us, the contractor made the arrangements and we paid for the rental via the contractor. The contractor told the renting business that we were tax exempt. The renting business refuses to remove the sales tax.
Short answer: You can't find anything to verify that claim because what is claimed is wrong.
Long answer: The rental business may be wrong, but I can't blame them the way I can blame someone for parking in a "No Parking" zone.