There are two main definitions so far as slang or Ebonics are concerned.
1.) When referring to a woman it means that she is a 10 on a 1 to 10 scale.
2.) As far as illegally obtained drugs are concerned it means a volume of the drug that is equal to approximately ten dollars. Generally used in reference to marijuana.
1.) Check out that dime ass bitch.
2.) Can I get a dime bag of that kush?