Tolerances - Published Minimum Altitudes

If assigned IFR altitudes can be considered to have a tolerance of +/-
200 ft before you are "busted", what applies to published minimum
altitudes other than DH and MDA on approach plates? Most people will
say that you are not supposed to descend any amount below the DH/MDA
altitudes. Does this also apply to procedure turn altitudes,
transitions etc.? Is there a tolerance that is in effect +200 -0 that
applies?

In practical terms, whereas a decent of 100 ft below an assigned
altitude will cause no problems, is such a decent of 50-100' below a
published procedure turn altitude, transition altitude enough to get in
trouble?

John