In Quebec, we have a combined tax rate of 14.975%. CiviCRM rounds this to 15%.
How to reproduce:
- Create a tax of 14.975
- Create a priceset with a text field of 1$
- CiviCRM will display: 1$ + 0.15$ Sales Tax
- Enter 100$ in that field, and CiviCRM will calculate 15$ taxes.