The claim
“Roman soldiers were paid in salt, which is why we say 'salary'”
Myth
'Salary' does come from the Latin for salt, but the idea that soldiers were paid in salt has no basis.
What's really going on
The word part is true: 'salary' comes from Latin salarium, "pertaining to salt". Nobody knows exactly how salt and pay became linked, and the popular claim that legions were paid in salt is called baseless.
The receipts
“The word "salary" comes from Latin salarium 'pertaining to salt' (sal 'salt'), but the exact connection is not known; a persistent modern claim that the Roman Legions were sometimes paid in salt is baseless.”
More myths
Myth“Bulls charge because they hate the color red”Bulls are dichromatic, a kind of color blindness, so the red of the cape is irrelevant to them. Myth“Goldfish have a three-second memory”Goldfish remember things for months, not seconds. Disputed“The Great Wall of China is visible from space with the naked eye”Not the way the legend says. It's too narrow and blends into the land, and astronauts disagree about whether they've seen it.