"Keep tabs on"

Does anyone know the origin of the phrase "keep tabs on" (to monitor)?

It comes from keeping accounts, maintaining records of charges. The Oxford English Dictionary labels "tab" in this sense as U.S. colloquial and defines it as "A table, an account [cf. TABLET . . . ]; a check." The earliest use of the phrase recorded in the OED is dated 1889: "Every man keeps a mean little tab in his head on his fellows" (Washington Post).