What makes the solution difficult is how many orders a customer can have.
What I would suggest, is to use an array (unfortunately, I don't use these) or a delimited string. The array, I think allows you to resize it. If you know the max number of orders, you can either 1 set the array size, set the delimited string, or set a list of shared variables.
regardless, of how you store the data, the next step would be in the group footer to create a formula that will increment the array/string/shared variable.
At the end of the report, you would have a several formulas to display back the results of the array/string/shared variables.
Sorry I can't be more specific, without knowing a limit, it becomes hard to determine a solution.