Hi Jennifer,
I did some quick test based on your request.
Created a program and added a project and an idea with cost data.
The rollup is OK.
Only thing to take into account is the allocation field at the hierarchy.
If the allocation % figure is 0 no rollup happens.
If the figure is non 0, then based on that figure a proportional part of the cost is rolled up.
If the figure is 100% then the whole cost figure is rolled up.
If the figure is 50%, half of it will be rolled up
Hope this helps