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.
Among the states with a general sales tax, Massachusetts (15 percent of revenue) relied least on sales and selective sales tax revenue. Every state and DC collected some revenue from selective sales taxes, with average revenue from such taxes accounting for 8 percent of state and local own-source general revenue.