You can set the price for an
item type to be dependent on the quantity of that type the
customer is renting. For instance the 3rd new release might
be less than the first 2. And depending on how many days the
customer is renting for, the program will use the
appropriate column.
There is a matrix tool button so you
don't have to fill everything out by hand.
Remember, the matrix is only for overriding normal
prices, otherwise you will not need it for simpler pricing.