How to not calculate hidden fields

Yes, I attached the link to the web form,

It's kind of hard to explain.

We are trying to show when a person clicks on a certain amount of days for renting our products that they will get a certain discount.  but we need to have at least 5 lines so that people can choose a different types of products 

Dropdown Field

Child Kayaks $145
Adult Kayaks $165
Double Kayaks $265
Paddle Boards $195

1-2 Days normal price

3-4 Days 25% off 

5-6 Days 30% off

7+ Days 50% off   

The only way I could figure out how to do that per line is to have 4 different fields in the total column overlapping them all and putting conditions to hide if those days aren't clicked in order to show the correct discount % 

1-2 Days normal price  (QTY1 * Dropdown1 *Days1) Hide is Any Days1 is greater or = 3

3-4 Days 25% off  (QTY1 * Dropdown1 * Days1 * .75)  Hide is Any Days1 are less than or = to 2 & greater or = than 5

5-6 Days 30% off  (QTY1 * Dropdown1 * Days1 * .60)  Hide is Any Days1 is less than or = to 6 & greater than = 7

7+ Days 50% off   (QTY1 * Dropdown1 * Days1 * .50)  Hide is Any Days1 is less than or = to 6

The problem is that when I want to do a grand total field for the 5 lines it still calculates the hidden ones too.

Grand total [3-4 Days 25% off] + [5-6 Days 30% off] + [7+ Days 50% off ] + [1-2 Days normal price]

Click link below

AKC OFFICE LAKE GEORGE Kayak Paddleboard Agreement