As far as I know tax/shipping calculations must be done on my site before I process a mobile transaction. Can somebody outline the work flow for how this is done. I know paypal has the address information which I collect of the transaction. Where do you make adjustments to the price for shipping (based on location) and tax (also location). Do people usually create a "information collection" page where I determine thine before I transfer to paypal, or is there another method people are using. Thanks.