This example lets you sell in lots of five, six, whatever, without the customer being able to mess things up by hitting the "increase/decrease quantity" button in the cart display. They are instead presented with a button they can click which will remove that item from the cart and take them back to your page where they can re-select a new lot size.

[Use of the =CA= tag for quantity adjustment control.]
[Use of the "parturl" tag for linkback to the item from the cart display.]