It seems with UPS, you can get an accurate shipping amount ONLY if you have Dimensional Shipping turned on and only have 1 product
Have multiple products with dimensional shipping turned off.
Using UPS.COM and our negotiated rates to determine accurate shipping cost for UPS.
With dimensional shipping off, orders with multiple products calculate properly. With it on, it calculates each item shipping individually as if shipped separately. For 4 items in one order, this resulted in about 400% increase over actual shipping cost. Not good.
However, if you turn Dimensional shipping off to fix this problem (which is does), then an odd shaped object that comes out on UPS.COM as $45 shows up as $19 online and my customer loses a lot of money on that order.
USPS doesn't do this and UPS website doesn't do this. It appears the software is doing what it's supposed to, as I can get a correct price in each instance by changing the settings, but there doesn't appear to be a way to offer accurate pricing with UPS that will account for both Odd shaped items (dimensional weight) and multiple item orders. If dimensional weight could be separated from individual shipping costs, as USPS does, that would work.
Anyway, just a hope for a solution at some future update. In the mean time, we have some hard choices to make whether to continue to offer calculated shipping costs or just go calculated shipping which requires us to go Offline Credit Card processing because there's no way to compute an accurate shipping price online for UPS for our entire product set.