Suppose that you are quoting a product with the following values:
If you change the Quantity to 2, Salesforce® will adjust the List Price down to $5.00 so that the Total Price stays at $10. (See the Salesforce API documentation for details.) This may not be intuitive for most users. If you define Quantity and List Price in ActionGrid℠, the Total Price updates accordingly. In this example, increasing the quantity to 2 will update the Total Price to $20.
If you prefer the default Salesforce behavior, then only define the Quantity. The List Price will adjust down in order to keep the current Total Price.