Here's the URL http://www.veggiediner.com/wp/?p=151
of our webstore. I needed to put it 'live' but it still seems like it's not calculating tax correctly in Google Checkout (GC) in some situations.
The behaviors seem different than you described. The (ecwid) Store does not require customer information such as shipping address prior to selecting Google Checkout (I do not have 'customer must create account to place order' activated because MOBILE orders are disabled with that setting), nor does Google Checkout appear to go back to Ecwid to finish the order process.
I checked with our accountant, and he indicates that as an located Illinois business, the shipping destination dictates sales tax. So regardless of the Customers billing address, out of state destinations are NO tax, in state destinations (regardless of Billing address) are WITH tax.
The 4 scenarios and GC's apparent behaviors are thus:
BILLING ADDR within IL + SHIPPING ADDR within IL = GC correctly applies tax
BILLING ADDR outside IL + SHIPPING ADDR outstide IL = GC correctly applies no tax
BILLING ADDR within IL + SHIPPING ADDR outside IL = GC incorrectly applies tax
BILLING ADDR outside IL + SHIPPING ADDR within IL = GC incorrectly does not apply tax
Google Checkout seems to be only going by billing address (despite an explicit option to go by shipping address instead). Although, sometimes it seems to get information from Ecwid if the shipping estimator is used. The problem is that the shipping estimator seems to retain information from previous sessions which is sometimes wrong.
GC has an option to apply tax rules IF the store software does not provide tax information. I have tried GC with rules activated and without rules activated, and neither seems to work correctly by shipping destination. It's starting to seem more like a GC problem than an Ecwid problem.
Is there some way to require customer to create an account and input shipping information prior to going to GC, but still allow MOBILE users to place orders (and that does not require customer to repeat entering the same info again if signing up for Google Checkout for the first time.)