Need to base taxation on Billing Address

[markw10]

I am close to launching my new website but ran into one problem. Unless I'm doing something wrong it appears that my taxing is being based on the shipping address of the product, not the billing address.

I am in Colorado and just need to collect taxes in Colorado. It appears many states are changing to a destination based system but unfortunately Colorado is still on a point of sale system. Of course I know in some occasions point of sale may not match the billing address if for example someone is out of town making a purchase.

From my testing though with doing a sale where I purchased as being in Colorado but shipping outside Colorado it charged no taxes but yet when I was outside of Colorado and shipping to Colorado it charged taxes. Is this how it works?

My question, is it possible for me to set it up to charge by billing address or is this impossible? I know I may not get many purchases like this but the only easy way I could think to avoid this is ship to billing address only which I don't want to have to do.