Calculated fields and hiding fields

I have a contract that is calculated out but I have multiple packaged for a client to pick which includes some prices and excludes other I am looking so see how to add a button or something that will hide fields I do not need but will recalculate and give you a total.

Example there are 5 expenses

Package 1

Expense1

Expense2

Expense3

Expense4

Expense5

Total Expenses(1-5)

Package 2

Expense1-Hidden

Expense2- Hidden

Expense3

Expence4

Expense 5

Total Expenses( 3,4,5)

I want to do this on one form I tried the hide/show field but it just hid them and wouldn't let me change the hidden fields once chosen and my totals would not change