No, not that I know of.
If I was you, I would get the lowest price using the above function. Then average it by mall_price().
This will give you the average between the lowest and the 5th highest.
It may still not work, I am not sure how often mall_price() actually fetches a new price. It may only do it once a day/hour/week/month/leapyear?
It looks like you need to find another tool to do this, you are not the first to ask these questions. If I remember right someone else was trying to do exactly the same thing about 6 months ago and ran into similar issues.