db lookup for POS system

We have a online store that uses a web assist shopping cart system. We are opening a store and I plan to use the same backend as a POS system. I plan to create 1 page though for store employees to key in item #'s and take Payment information. The project I need help with though is when a product ID is entered in the form, I need the db to fill in the product name, price, etc. on the form and then tab to the next line. ? I also need a dynamic sales tax and total to update as each item is entered. Our site is ASP VB and the db is mysql - I host my own servers so anything is possible, but I'd prefer to see a javascript based solution. ## Deliverables I can be reached by phone or email. ? If this is more complex, I'm flexiable on the design.