Tax problem In the store section?

Okay, I will try to explain this as clearly as I can,

I purchased a z2, and the tax showed up on the order review section (with all the prices and subtotal). Upon adding a shipping type, the tax section completely disappeared. So the price was 799.99 Plus the next day shipment cost, and there was no tax. So I smiled and thought that the cost was 824 and some cents. The tax then got added in AFTER i submitted my order. It was just a little frustrating because I ended up spending 894 and some change rather than 824. I just wanted to let you know. thanks djtt! Looking forward to the z2.