My shipping policy states 100% amount listed for first most expensive item, then 50% of the amount listed for all other additional items.  If you take one of the items that are flat rate (now $9.95) additional items are only $1 ea assuming they fit into the package and the total price comes to less than $100.  I try to limit shipping to $100 packages.  I cannot mix media mail with regular mail. 

Most groups are shown as a group then I zoom in item by item.  total scv is shown from a recent catalog on most items.  Many of my discount postage lots are collectable and will sell over face.  this is not discount postage.  All items on my page are relisted till sold with a very often price reduction if appropriate.