"Factoring" means a method by which the taxpayer may determine the amount of the tax when the tax is collected as an unspecified part of the selling price.
To calculate the tax under the factoring method, the total cost to the consumer is divided by one plus the cumulative amount of the state and applicable county, city, and town tax rates, stated as a decimal. The result of this calculation is then multiplied by the cumulative tax rate to arrive at the amount of the tax on the sale. The gross receipts subject to tax, plus the cumulative tax on that amount, shall equal the total cost to the consumer.
To factor:
Total cost to the consumer $105
Divide the total cost to the
consumer by 1 plus the tax
rate (1.00 plus .05)
$105 divided by 1.05 equals the
price of tangible personal property $100
Tax as calculated ($100 times 5%) $5
Ariz. Admin. Code § R15-5-2210.01