If you itemize, you can definitely count the sales tax paid as a major purchase and take the sales tax paid as a deduction. Also, you may qualify for a tax credit for your roof. Remember, when calculating the energy credit, only the roof (without tax) qualifies, not the installation costs.
Roof requirements: "Metal roofs with appropriate pigmented coatings and asphalt roofs with appropriate cooling granules that also meet ENERGY STAR requirements."
The manufacturer of the roof also needs to supply a statement certifiying that the roof qualifies for the credit. Here's what the Energy Star website states:
"A Manufacturer’s Certification Statement is a signed statement from the manufacturer certifying that the product or component qualifies for the tax credit. Manufacturers should provide these Certifications on their website. Call the manufacturer, or search their website. EPA does not have copies of the Manufacturer's Certification Statement. Taxpayers must keep a copy of the certification statement for their records, but do not have to submit a copy with their tax return."
