dime bag

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A packaged amount of an illicit drug sold for ten dollars or another fixed price.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A small Ziploc bag containing ten dollars worth (usually one gram) of marijuana. This may refer to the unit of measurement or the bag itself.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun street name for a packet of illegal drugs that is sold for ten dollars