Shipping to Amazon FBA

Hello all,

I just got into FBA and I am currently shipping to an Amazon directed distribution center via UPS. I have a 85 lb total shipment weight and was wondering if it mattered how many boxes I ship it in. Obviously my first choice would be split the weight between two boxes; 42.5 lbs each. But I was wondering if it would cost more if I shipped it in 3 boxes @ 28lbs each?