Doxycycline is used for malaria prophylaxis or treatment. When it is administered for treatment of P falciparum malaria, this drug must be used as part of combination therapy (eg, typically with quinine or quinidine).
If you buy goods and are not charged the Rhode Island Sales Tax by the retailer, such as with online and out-of-state purchases, you are supposed to pay the 7% sales tax (less any foreign sales tax paid) for these items yourself as the Rhode Island Use Tax.
2016 List of Rhode Island Local Sales Tax Rates. Rhode Island has state sales tax of 7%, and does not allow local governments like cities or counties to collect a local sales tax. Therefore, the sales tax in any city or county in Rhode Island is a flat 7%. Last updated April 2016.