How much do income taxes cost? Sales tax?

As with any law, there are costs in enforcement and regulation. I'm curious, if anyone has done a detailed study of what compliance with income tax laws in USA actually cost in terms of man-hours and dollars spent in all aspects of legislation, enforcement and compliance?

For instance: I just spent a total of 4 hours filing my federal tax return. Much of that time was answering questions and copying w-2's on H&R block's website, logging in to my online accounts with various banks for my 1098s and making sure that my whopping $27 return was correct (i do like not overpaying too much during the year). However, this time spent is added to by the HR department and accountants where I work, payroll company they use, IRS agents and oversight agents to make sure we all got it right, the audits and resulting trials of some cases, the time and money spent in training for everyone involved... all due to the time spent generating the legislation that produced the nesessity of this work load on all the rest of us.

How about sales tax? When it is calculated automatically at a cash register and sent off to the governmental agencies in each state there isn't much time spent. But when companies deal with sales across state lines and outside the country I know things get much more complicated. There are 4 full time accountants where I work that do nothing other than process orders and apply sales and transportation related taxes (including researching laws).