Proponents of a Denver ballot initiative want to add another 1.5 percent to the local marijuana sales tax to fund pandemic research, and they almost have enough signatures to put that proposal in front of voters. Recreational marijuana purchases carry several layers of sales taxes in Colorado, at both the state and local levels. In Denver, there is currently a special marijuana tax of 5.5 percent on recreational pot sales, combined with a standard 4.81 percent retail sales tax, amounting to just over 10.3 percent. Now the campaign for the Denver Pandemic Fund believes the time is right to raise Denver's special marijuana tax to 7 percent, which would push the total local sales tax on recreational purchases in the city to just under 12 percent at the register.