I need to put prices with tax ...

Hello,

Thank you for your post. Tax settings is probably not working correctly. I will let it check by development, so it should be repaired in next version.

After more tests, it works, but it is not too much user friendly.
You can find settings in:
Object detail -> Prices -> Tax

Remember that item price you are setting here is value with tax.
Example:
Item price: 29 Eur
Tax rate: 10 (%)

When I buy 2 hours it is 58 Eur.
Total price = 58 Eur = 110%
Tax price = (58/110)*10

You can see tax price in reservation form.

We will try to modify it for next release which should be prepared next week.