If your shipping rates might change, you could put those values into a table and reference them as cell ranges.
      G	H
1   Pounds	Rate
2     1	6
3     7    	12.9
4     9	16
5     14	24.5
The the formula would change to:
=LOOKUP(A1, $G$2:$G$5, $H$2:$H5)

For these lookup tables, all we're setting in the first range is the starting point for each shipping rate