shipping costs acc to number of items

[americamba]

I'm sure this has come up before but I couldn't find it. I want to be able to give a break on shipping to those who order more. For example (the following is not my final desire but I will be able to see the general ideas of the code you might recommend):

 

1. based on amt of purchase: 1 item $2.50; 2 or 3 items $2.00 each; 4 to 6 items $1.50 each; 7 to 10 items $1.00 each. 11 or more free shippping.

 

2. or based on money spent: $10 or less $2.00 shipping; $11 to $20, $3.50 shipping; $21 to 30, $4.50 shipping; $30 to $50 $6 shipping; more than $50, free shippping.

 

Is this code lying around somewhere?

 

Thanks, Frank