Since setting up this site, we have processed 30 orders via the MarketPress eCommerce system. Today was the first time we had a glitch with the calculated shipping option. The customer purchased items which should have incurred a $7 shipping charge (the same products in the past have done this correctly). Instead, the customer received free shipping.
I have check all settings (even though they haven't changed) and made sure all plugins are up-to-date.
The website is http://www.savannahtearoom.com