Mixing products for larger orders allows you to benefit from a specific price tier without having to order multiple items of the same product. Here is an example of how this works.
MIXING PRODUCTS OF THE SAME PACKAGE SIZE
Some package sizes, like 5 gallon pails, have different price tiers based on quantity. This price tier applies to buying that quantity of any combination of 5 gallon pails, not that product only. So if you buy lets say 28 pails of any combination of products, you get the 28 pail price for all of them.
MIXING PRODUCTS OF DIFFERENT PACKAGE SIZES
If you mix product sizes in an order, then the individual price tier applies to each package size. For example, if you have 5 pails of different kids and 20 x 1 gallon sizes of mixed products, then the 5 pail price tier applies to the pails and 20 gallon price tier applies to the gallons, respectively for each size, regardless of the product type.