When Coloradans make purchases over the Internet from out-of-state companies such as Amazon.com and Overstock.com, they’re supposed to voluntarily submit sales taxes to the state. Few, if any, do, The Denver Post reports. A measure heading toward a final vote in the state Senate would attempt to change that by requiring companies to inform Colorado customers — both at the time of sale and at the end of the year — that they owe the state taxes on their purchases.