After doing some research I found that UPS doesn't bill directly based on dimensions but rather they figure out the billable weight based on dimensional weight. I had been sending the standard weight for items that UPS would calculate a dimensional weight using dimensions. You could read more over here on UPS's site.
Now, I still have to figure out by how much percent I should adjust the shipping cost buy. If I were to adjust the price by 10% (since I get a reduced rate from UPS) it would mean that a shipping cost of $250 would be reduced by $25 and a shipping cost of $25 would be reduced by $2.50. Now, my shipping cost varies on many different factors like the zip code being shipped to and billable weight. How to I get near the exact shipping price that comes up in my shopping cart?
Re: Bilibile Weight
the shipping-price per item must be either an exact match
or an overestimate for the majority of users within the
registered feed's target-country; there is no such concept
as "near the exact shipping price" allowed by the policies.
in this case, the best likely course is to calculate and submit
an overestimate for the majority of users within the u.s. for
such items; either via a shipping attribute or shipping_label
and corresponding account-setting.
otherwise, such items simply cannot be submitted.
also, be certain a direct-to-consumer shipping method is used --
items using other types of shipping (rates) cannot be submitted.
details are currently here --
otherwise, google should likely be contacted directly.