I want to set up flat rate shipping but charge an incremental price (same each time). For example, I want my flat rate to be $2.50 and then charge an additional $1.50 for each additional unit. So the total shipping price of two units should $4.00, three units should be $5.50, etc.
I followed Case A and Case B on your shipping calculator help page exactly and it's not working. It appears to be adding the $2.50 and $1.50 together each time and charging $4.00 for every unit (eevn the first one).
Can someone please help me?