There is clear documentation available to you to help educate your docs.
Anesthesia time is defined in the 2013 ASA RVU Guide top of page xiv:
Anesthesia time begins when the anesthesiologist begins to prepare the patient for anesthesia care in the operating room or in an equivalent area, and ends when the anesthesiologist is no longer in personal attendance, that is, when the patient is safely placed under post-anesthesia supervision.
Medicare defines anesthesia time similarly in the following link #50:
http://www.cms.gov/Regulations-and-Guidance/Guidance/Manuals/Downloads/clm104c12.pdf
There are instances of discontinuous time.......patient taken to the OR, given Versed and monitors applied, surgeon delayed due to an emergency and the patient is taken from the OR-sent to the Recovery Room or back to Same Day Surgery and brought back to the OR at a later time that day (just an example). This discontinuous time must be clearly documented; can only bill for time in attendance with the patient.
Page 58 or the 2013 ASA RVU Guide (1.2 and 1.3) also speaks to time-time spent on pre- or postoperative placement of a block for postoperative pain is separate and NOT included in reported anesthetic time while blocks placed after induction and before emergence DO NOT need to be deducted from reported anesthesia time.
It would appear from your examples the anesthesia time is being recorded pretty regularly on the "0" or "5". This practice is a red flag for an audit. If indeed, time in attendance with the patient were being accurately documented, the probability of all "0"s and "5"s would be virtually impossible.