I'm having trouble with the native quantity discount pricing. We use attributes in our products, but the attributes are free such as engraved text etc.. Most often, people add items to their cart one at a time in order to add different text to each item. When they get to a certain quantity we have set as a discount, that item gets the discount, but the others already added to the cart do not. Example:

Price is $10
discount of 10% at 6 quantity

When adding the item one at a time to the cart, we get 5 items priced at $10 and the sixth item priced at $9. All are the same product, just added to the cart one at a time with different attribute settings (free attributes, no charges).

Is there a way to make it discount the first five in the cart when a sixth is added?