Coffee usually _is_ a round number in my experience, and I know of people who aim for round numbers when filling their car, and of fuel stations which require a pre-set value, often 10, 20, 50€ etc
Yes, as your parent comment points out, the article centers itself on US transactions, where listed prices seldom include tax and are frequently a cent below a round number. For example, the menu says a dish is $15.00 but the restaurant charges $18.83 after tax and tip. Globally, there's no doubt the US is the exception rather than the norm.
That sounds reasonable for some states but 5 states have no sales tax
and many states have exclusions to sales tax. Many of those are also likely to have rural areas where small businesses like to use even amounts.
All of that is easy to account for, all of the metadata you need is available. This also applies to the sibling comment about rounding up to charity at the grocery store, the data is all there, even if it's e.g. the fraud analyst at the bank or credit card company instead of the fraud analyst at the grocery store.