ok, so you need a column for
in the add to cart button, set Quantity to be updaable from a drop down, set the qtyBreak1 column to be the first quantity selection and Break1Price to be the price for that selection.
set qtyBreak2 to the second selection and Break2Price the price for that selection.
after the form is created, populate the list with the 2 qty selections that should be available, and create a new calculation in the cart object as:
abs([Quantity] == [qtyBreak1])?[Price] = [Break1Price]:0
and another calcualtion as:
abs([Quantity] == [qtyBreak2])?[Price] = [Break2Price]:0