The sales tax thing works a little different here in the Mountain State. If I'm doing new construction or installing new circuits or equipment (not upgrading old equipment) I pay the sales tax at the wholesale level. I recover this as an additional 6% in my markup.
If I'm doing repairs or replacing old equipment, I don't pay sales tax at the wholesale level, but I'm required to charge my customer sales tax on everything, including labor.
It is a pain in the backside but this came about because of abuse of the previous system.
Tom