Different Price for location

One option will be to use the shipping methods for that:
You can create 2 manual shipping methods via the menu System->Shipping methods.
One for all of the world except hawaii with a price of 0 (so for that, you will have to create a new zone, via the menu System->Zones, including the zones your users are from except hawaii) and one for hawaii with a price of 3%. Then, you can go in the tab languages of the config and change the translations of shipping to something else like "additional costs" or whatever the 3% cost is. You will have to activate the option "Force shipping regardless of weight" as well in the config.

You're saying that you have a membership control system. Does that mean that your users can be in different groups ? If so, you could have one group of users for hawaii. Then, you could set different prices based on the group of the user when adding the prices to the products. There is an "access level" icon for that in the Business edition.