For Sellers:
In Seller hub......IF you have Shipping cost enabled to show in a column......and you use calculate.....
After Clicking on the word calculate for the item......it gives you a page to put in a ship to zip code......and then calculates the shipping to show both the buyer cost and the seller cost.

The one caveat is that it shows the real retail cost..... If you discount shipping, that amount is NOT shown....
Neither Better half nor I realized that until I was messing around today.....lol....... only been here 40+ years counting the two of us......