now it's split between Russia (for russian audience) and Netherland and Finland (for others). Also this https://sputniknews.com/world/20151024/1029057531/finland-he... may be interesting for you.
(Everything just works and there are no insane bribes to pay to various mafias.)
http://www.nytimes.com/2009/09/12/business/global/12ikea.htm...
Edit: there are many ways to hide bribes, of course. Typically it involves overpaying for something. It would be hard for even a non-corrupt tax authority to tell the difference between having bad negotiation skills and bribes.
Let's say someone claims that their programmer genius Ivan saved a company ~1m USD/year with latest commit; and awards him $100k. And you see this unusual bonus, how are you going to know 99% of that doesn't go to someone other than Ivan?
The direct bribes is really for low-level clerks like police officers or fire hazard inspector s.