Forty-three of the fifty states are pushing for an internet sales tax. They are hoping that retailers will voluntarily install software that will tax each purchase and pay it electronically.

The proposal is for the new system to initially be voluntary. "So (unless) Congress were to act and make this mandatory, there would be no penalties," says Peterson. But there's a plus for businesses who do adopt the software. The states say the electronic system is so good, they'll designate participating businesses "audit proof."

So unless retailers volunteer to collect taxes on behalf of the government, they will be subjected to targeted audits.