Why does it have to be small transactions? Every transaction, regardless of size, has a chance to end in anything from 0 to 99. The more items on your receipt the more chances to have different variations. Plus tax rate varies from area to area. I don't think that his assumption is that far off. But yes, he probably could have done something to get actual data.

It should be small transactions because cash is being used less and less often for medium-to-large transactions.

It's not safe to assume that all cent values from 0 to 99 are equally likely because of the fact that cash transactions tend to be small. The number of items being purchased will also tend to be small. So the fact that most prices for individual items tend to end in 99, 95 or some other multiple of five cents should have a huge impact on the distributions in real life, especially for transactions to which sales tax does not apply.

For example in Oregon, a state with no sales tax, the fewest number of items you'd be able to buy at $0.99 or $0.95 to get a $x.32 total is at least 20. (That's a whole lot of "fun size" bags of potato chips.) The total would come out to $19.32, at which point a lot of people would just pay with plastic, anyway. Perhaps most people would.

I suppose. I guess I use cash more than others. I would easily toss a $20 at a $19.32 bill.

I stopped reading after this and came here to say this :-)