These are from the fiscal tax stamp issue of 1916, which contains Scott #RA3 and #RA5. Only the 5b and 10b denominations were used as a tax on postage -- there were also 50b, 1l, 2l, 5l, and 50l denominations, which were used to pay the tax on railway fares, theater tickets, etc.
Scott only lists the postal issues, 5b and 10b.
The entire 1916 fiscal tax set is illustrated here:
http://www.romaniastamps.com/charity.htm