Ontario provides a point-of-sale rebate of the 8% provincial portion of the HST for all Ontarians on specific items such as:

books
children’s clothing and footwear
children’s car seats and car booster seats
diapers
qualifying food and beverages
newspapers

In the food and beverage category, qualifying prepared food and beverages that are ready for immediate consumption and are sold for a total price of $4 or less are to be charged only 5% tax instead of 13%. because this tax rule is dependent on the subtotal of the whole order and not each individual item, it makes calculating the taxes properly next to impossible.

for example:
a customer wants just 1 coffee for $1.99 - tax is only 5%
a customer wants 1 coffee $1.99 and 1 muffin $3 for a subtotal of $4.99, therefore the whole order needs to be taxes the full 13%.

To accommodate this I'm stuck having to make multiple buttons for the same item with different taxes attached.