When you set the price for a book in the US on the Apple iBookstore, the price does not include any sales tax. So, if you set the price at $4.99, Apple will send you $3.49 for each sale (70% * $4.99 = $3.49).
If you set the price of your books in Europe, something very different happens. Apple has cleverly based their European operation in Luxembourg which has the lowest taxes in Europe. Nevertheless, Apple is required to do two things: collect Luxembourg’s 15% VAT on digital books and advertise books with that 15% already included in the price.
What Apple doesn't make very clear, in my opinion, is that when you choose the price for your ebook in European iBookstores, you are choosing a price that already includes that 15% VAT. So, if you quickly convert your $4.99 into 3.65€, you might be tempted to choose an iBookstore price of 3.49€ for Europe. But you should know that .45€ of that amount is VAT and so the actual price of the book would only be 3.04€. This will become all the more clear when you get your sales reports from Apple and they only give you 2.12€ ($2.89) for each sale (which is roughly 70% of 3.04€, and only about 60% of 3.49€).
To figure out a better equivalent for your $4.99 book, do this:
1. Convert $4.99 to euros (google “$4.99 to euros” for a rough estimate): 3.65€
2. Multiply price in euros by 1.15 (adding 15% to price): 4.20€
3. Look for closest matching price tier in iTunes Producer: 3.99€ or 4.49€
One way to see what Apple will send you for each sale is to click on the question mark next to the Price Tier field in iTunes Producer or in iTunes Connect:
When you click the question mark, you'll see this list of Price Tiers and “Your Proceeds” which is how much Apple will send you for the sale of each book. Note that for EU customers, it's always 70% of the Tier price divided by 1.15 (70% * (Tier/1.15)).
Note also that if you click any Price Tier in the list, your book will be automatically and immediately updated to that Price Tier. No additional OK will be required, and no Cancel is available. To go back to the original price, you'll have to reselect the original price.
This same pricing issue also occurs with the Australian iBookstore (where the price you set includes about 10% tax).
This article is meant to be orientative, not definitive. I'm not a lawyer, tax or otherwise, or an accountant. You should consult one of those if you have doubts.