Display prices with tax confusion

On a Zen Cart v1.5.4 site with the following configuration settings:
Configuration->My Store->Display Prices With Tax = true
Configuration->My Store->Basis of Product Tax = Shipping
Locations/Taxes->Zone Definitions ... Australian Zones => Australia/All Zones
Locations/Taxes->Tax Classes ... Taxable Goods
Locations/Taxes->Tax Rates ... Class = Taxable Goods, Zone = Australian Zones, Rate = 10%.
All products are Tax Class = Taxable Goods.

There is one product with a $3.00 gross price, including tax, (after discount). On initial entry to the site (not logged in), the product's price displays as $3.00 (as expected).

If I log in, the price is now displayed as $2.73 (as expected, the price without tax, since my primary address is not in the Australian Zone).

If I place that product in my cart, start the checkout process, change my shipping address to an Australian location and then return to shopping, my expectation is that I'd be shown prices with tax since my shipping address is now within the taxable-products' zone. The prices, however, do not include tax.

The prices do show with tax within the checkout process (once I've changed my shipping address to the Australian address).

Am I totally off-base here (it's surely happened before!) or should the product prices be displayed with tax once I changed my shipping address to be in Australia?

Changing your shipping address during checkout is applicable for that order only. Try changing your shipping address on your account. Go to "my account" and update the address.

Louis:

Changing your shipping address during checkout is applicable for that order only. Try changing your shipping address on your account. Go to "my account" and update the address.

I think the point is that as a customer that has chosen a shipping location and decided to add something to the cart, now everything looks off and is a potential possibility of losing the shopper, or at least receiving complaints about the issue.

If modification of "my account" information is the only way to have it appear, then either the stored data would probably need to be updated upon each destination change (also adds problems) or at the very least SESSION data needs to be updated to account for the change in shipping location so that prices/taxes are displayed correctly. Or the price display should be based on a series of data and note all of the settings that are identified to line up for this issue. Whatever complexity is involved, it appears that during store navigation (before the checkout process) that in the above scenario if the shipping location has been identified the prices do not adjust for tax accordingly.

mc12345678:

I think the point is that as a customer that has chosen a shipping location and decided to add something to the cart, now everything looks off and is a potential possibility of losing the shopper, or at least receiving complaints about the issue.

If modification of "my account" information is the only way to have it appear, then either the stored data would probably need to be updated upon each destination change (also adds problems) or at the very least SESSION data needs to be updated to account for the change in shipping location so that prices/taxes are displayed correctly. Or the price display should be based on a series of data and note all of the settings that are identified to line up for this issue. Whatever complexity is involved, it appears that during store navigation (before the checkout process) that in the above scenario if the shipping location has been identified the prices do not adjust for tax accordingly.
Thanks, mc12345678, that pretty-much summarizes my concern.

Once the customer has signed in and started the checkout process, the $_SESSION['sendto'] variable is set to the customer's shipping address. That's the address that "drives" the prices during the checkout process. I'm thinking that, if set, $_SESSION['sendto'] should drive the prices displayed everywhere, given the other tax-related configuration settings.