We think one of the advantages of deep LBYM living is that highly accurate tracking of the smallest bars on your personal spending Pareto chart becomes meaningless, ... Therefore we keep track of items paid by CC, direct deduction or check (because there is little effort involved) but are more than content to let small cash purchases fall into a single misc bucket.
+1
For a couple of years, a few years back, we tried to track *everything* to the penny. We just put everything manually in a spreadsheet, so it was a big pain. We were already pretty well aware of significant recurring expenses as well as any individual expenses of consequence. A frugal lifestyle doesn't present that much opportunity for unexpected day-to-day leaks. We might have had a couple of surprises, but nothing we'd change our behavior over.
Now we just use the one bank statement (through which everything else ultimately runs) to come up with an accurate annual figure. That plus the pay stub (for withheld items that don't make it into the bank) gets us close enough for estimating total household expenses that will need to be covered in retirement.
The detailed process was perhaps instructive and reassuring, but in our case not very helpful for a continuing effort.