Tell us therefore, What thinkest thou? Is it lawful to give tribute unto Caesar, or not?
But Jesus perceived their wickedness, and said, Why tempt ye me, ye hypocrites?
Shew me the tribute money. And they brought unto him a penny.
And he saith unto them, Whose is this image and superscription? They say unto him, Caesar's. Then saith he unto them, Render therefore unto Caesar the things which are Caesar's; and unto God the things that are God's. ~ Matthew 22:17-21 KJV
"Tribute" in this case means a "tax", or the money with which the "tax" is paid.
So, was the money in question Caesar's? Probably not. It would be very unlikely for it to have been.
First of all, government-- "Caesar"-- possesses nothing it didn't either steal or buy with stolen or counterfeited money. Even the money it prints, mints, and programs into existence. The metals, the mints, the printing presses, and the computers were ill-gotten. A thief doesn't own the stolen property he possesses. The money paid to the employees involved in creating the physical and virtual money is in the same category. Does the thief own something he makes from stolen materials with stolen tools? Obviously not, or property rights mean nothing.
The money isn't Caesar's property and isn't owed to him.
Even if the money did originally belong to Caesar, once he trades it for a product or service it is no longer his, no matter whose picture is on it. If I paint a self-portrait and sell it for $10, the portrait no longer belongs to me. I can't just go and take it and holler "Taxed!" and be in the right. It is no longer my property even if my picture is on it.
So, yeah, if you possess something which legitimately belongs to government (or anyone), give it back. It's not yours. Render it unto its rightful owner. But "tax" money isn't government's. "Taxation" is still, and always will be, theft. "Taxation" is never ethical. No "law" can change that.