Paypal module always sends net price and tax

In case of a bad run of number_format my net.price+tax isn't the same as my price that shows up in the shop for customers. As the paypal module always sends the net+tax combination it sometimes creates less money than expected.
Is it possible to send paypal the final price of the product?
For example I have a product for 890 Incl. 27% tax. Price in the admin: net 700.79 890
Paypal gets these prices: Net: 700 Tax: 189 Total 889

I don't want to have prices like 889.
The Paypal module should only send prices incl tax without specifying tax if your order contains discount. As of the condition on row 85:

    // Build cart containing discount - no tax specification supported
      if ($order_contains_discount) {

This is because Paypal doesn't support tax for negative values (discounts).

If your order does not contain tax, then my first guess is you have tax included your product price. All prices must be inserted to database without tax. What have you set for product price when editing the product?
I've stored product prices as net price and set tax according to the tax rates of different product types. (We have 27% and 0% as well.) As of the example above I have a net price 700.79 because I would like to sell the product for 890.

I think the problem is that I couldn't give paypal decimals because it give me an error. Tha solution was to cut down decimal places from the net price but this give a wrong final price of course. How can I send at least two decimals to paypal to calculate the correct final price or send it the calculated final price?
I'm afraid Paypal doesn't support displaying gross amounts unless you skip the tax parameter completely like how data is sent upon discounts. Have you asked Paypal if there is such a display setting?