Denver City Council will consider asking voters to approve a 5 percent sales tax on retail marijuana and the authority to raise the tax as high as 15 percent.

A 5 percent tax would raise the cost of an eighth of an ounce of marijuana to $30.66 from $25 now, a total that includes state sales and excise taxes that also must be approved by voters.

New taxes that would begin to be imposed in January are meant to offset costs the city believes will come with the sale of marijuana to anyone 21 or over — expenses the city says will include more police, anti-drug education campaigns and improved oversight.

Some worry, however, that city and state taxes could drive the business back to the black market.

Michael Elliott, director of the Medical Marijuana Industry Group, said the industry already is the most taxed business in the country because of a federal law prohibits marijuana businesses from taking tax deductions.

On Monday, the city council met in a committee to decide what to do about a tax.

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