CalculatePrice will calculate the final total price.

FixedMemberDiscount represents a fixed discount given to members.

ItemPrice is the price of a single line item.

MemberDiscount represents a discount given to members, either fixed or a percentage.

PaymentMethods settings.

Price represents the total price of all line items.

PriceParameters represents the order information to calculate prices.

Settings represent the site-wide settings for price calculation.

Tax represents a tax, potentially specific to countries and product types.

Coupon is the interface for a coupon needed to do price calculation.

Item is the interface for a single line item needed to do price calculation.