The SHIP550 is only good for 5# or less so you are correct, it depends on what powder's are ordered. I just ordered 10# for a group buy, including 3 Candy colors, and the discount was $20. I could've split the order into 2 - 5# order's but the savings would've only been $1.35 using the SHIP550 code twice (since their rate for the 10# order was $12.35 for a USPS Medium Flat Rate Box).