You buy spice by the pound and resell it by the ounce.

 

In Acme Setup Information >POS Options 3 tab set "Get PLU Quantity Factor From" to "PLU Selling Quantity".

 

Se up two units of measure:

 

 

 

Set up item like this:

 

 

If you also sell 1 pound bags:

 

 

 

One pound bag, discounted price: