Calculating Store Comission Fees

Hello. 

Here's what i got:

Seller | Store | Revenue 

1             2         1.200

2             2          800

3             1          300

4             1          500

I want to create a measure that calculates the comission fee i have to pay for each seller, respecting the following criteria:

If the total revenue of the store was greater than or equal to 1.000, the fee is 5%

If the total revenue of the store was less than 1.000, the fee is 2.5%

And then, i want to show a table with sellers, stores, revenue and comission as columns.

My main problem here is that, when i create this table, my actual measure changes the calculation of the comission fee to each seller individual revenue, not the total.

I am using something like:

if(sum(revenue)>1.000,0.05,0,25)

is there any way to this measure only apply to the store and not to the seller level?