I was testing if Vendio Coupon can be used during Google Checkout but observed one strange behavior.
The Google checkout seems to accumulate shipping costs (does not reset to 0) if the buyer does not complete the checkout process, and then return to vendio store to revise shopping items.
This is the scenario:
1. Add one item in Vendio shopping cart, select Google checkout.
2. Login to Google checkout.
3. Google calculate the total. write down the item cost and the shipping cost.
4. Close browser.
5. Open browser again and get back to vendio store.
6. If the item still in shopping cart, remove the item.
7. select one item in the shopping cart again. Then select Google Checkout.
8. Google calculate the total. Observe the item cost and shipping cost. The item cost is correct. However, the shipping cost is accumulating.
9. You can repeat step 4 to 8. The shipping cost will be adding up.
I am not sure if this is Google's bug but please check if this is related to Vendio.