Minimum bid on Adwords is 5 cents (right?) Revenue share of 68% means roughly 3.5 cents (right?)
Why do people (Adsense Publishers) report 1 cent clicks?
Well for one thing, your premise is wrong. There hasn't been a five cent minimum on bids for years. I bid lower than that all the time. The ad served could have been from a different network with a different rev share. It could be a CPM ad. There's rounding and fractions. All kinds of reason.