Now, here's where the rub comes in for me - if I pick up materials at the supply house, pay the sales tax up front, and if I mark up the materials for a profit, the State wants their "VIG" on the difference between what I paid (with the sales tax) and what I charged. What a crock !!! So, the way around that is to have the supply house not charge you any sales tax, mark up the material for profit and then charge your customer sales tax on the materials at the time of installation.
Here's how the math works out - if I buy material for $100.00 and pay 7% State sales tax the material costs me $107.00 (so the State gets $7.00 on the sale). If I mark up the material at say 20% I then sell it to my customer for $128.40 (the State wants an additional $1.50 on the $21.40 difference ). If I buy the material at $100.00 and pay no sales tax, mark it up 20% and then add the sales tax the total still comes out to $128.40 but the State would get $8.40 instead of $7.00.
IMHO, the only way to beat them is to out-earn them.