Calculating Discounts, Surcharges and Taxes

Here is the breakdown of how Rerun calculates discounts, surcharges, and taxes on a payment stream or one-time payment:

Base Amount: ($)	$100.00	Total Item Value or Base Amount entered.
Discount: ($ or %)	$5.00	Subtracted from Base Amount.
Credit Card Surcharge: (%)	2.50%	Applied to discounted price but before tax is applied. (i.e. $100 - $5 = $95 * 2.5% = $2.38)
Tax 1: (%)	5.00%	Applied to the discounted price or base amount, if no discount is given, plus the credit card surcharge. (i.e. $100 - $5 = $95 * 2.5% = $97.38 * 5% = $4.87
Tax 2:(%)	0.00%
Grand Total:($)	$102.25	Total base amount or item total minus (-) discount plus (+) credit card surcharge plus (+) taxes.

Rerun allows you to add credit card surcharges now to your Rerun payments, however, there are some rules and regulations that you must follow within the U.S. If you add a surcharge to a payment, you are responsible as the merchant to adhere to any laws/regulations surrounding surcharges.

What is a Surcharge?

A credit card surcharge is a fee that a retailer adds to the cost of a purchase when a customer uses a credit card. Surcharging isn’t allowed everywhere. Currently, there are laws limiting surcharging in: California, Colorado, Connecticut, Florida, Kansas, Maine, Massachusetts, Oklahoma, Texas and Utah.

and

http://www.creditcards.com/credit-card-news/credit-card-surcharges-allowed-1281.php