I would keep them at least seven years, some of the individual receipts maybe you don't need after 4 years or so. And that is tax years, not calendar years.
Since the business has been sold, I do not think you need to keep anything indefinitely.
You only need to keep records to track the basis of a item, once it is sold you do not care about the basis after seven years.
I am not an accountant, but I did stay at a Holiday Inn Express a while back.
FIRE no later than 7/5/2016
at 56 (done), securing '16 401K match (done), getting '15 401K match (done), LTI Bonus (done), Perf bonus (done), maxing out 401K (done), picking up 1,000 hours to get another year of pension (done), July 1st benefits (vacation day, healthcare) (done), July 4th holiday. 0 days left. (done) OFFICIALLY RETIRED 7/5/2016!!