There's a bill in the state legislature that, somewhat surprisingly, made it through its first committee vote. It would reduce the "swipe fees" paid to credit card companies by barring the companies from charging the fee on the part of the total charge represented by sales tax. It is not specific to the restaurant industry but they seem to be the biggest champions of the measure.
Sonia Riggs is President and CEO of the Colorado Restaurant Association and is in favor of the bill.
Denver Restaurant Owner Supports the Swipe Fee Relief Act
The bill's page at the state legislature website: SB26-134 Payment Card Networks' Fees | Colorado General Assembly