Chris Castleman, owner of the Fiddlehead Cafe in Mendocino, told NBC News the extra charges would be donated to charity.
"I don't think $5 to charity is too much to ask from mask-wearing customers who claim to care so much about the community they live in," he said. Masks, he continued, are "ineffective government measures" that have caused "collateral damage."
Castleman had to shut down his business last June, when lockdown measures in California were much stricter than they are currently, and dining while masked was not an option.
The shutdowns hurt businesses, Castleman said, and "everyone wearing a mask is complicit."
His imposition of a new 'mask tax' is in response to the Centers for Disease Control and Prevention's recent updating of its guidance on wearing masks, which states that fully vaccinated individuals can cease mask-wearing and social-distancing.