This is the same problem as described in #14440 but with Timestamp, and the fix should be similar.

Probable source of error: https://github.com/pandas-dev/pandas/blob/093aa8231eae92ff6cf7ef9564d62289b458aaff/pandas/tslib.pyx#L438

A small, complete example of the issue

In [1] import pandas as pd
In [2]: ts=pd.Timestamp('2016-03-06 18:43:45.950000')
In [3]: ts.floor('10L')
Out [3]: Timestamp('2016-03-06 18:43:45.950000128')  

Expected Output

Timestamp('2016-03-06 18:43:45.950000')

Output of pd.show_versions()

INSTALLED VERSIONS

commit: 093aa8231eae92ff6cf7ef9564d62289b458aaff python: 2.7.6.final.0 python-bits: 64 OS: Linux OS-release: 3.16.0-46-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: None.None

pandas: 0.19.0+63.g093aa82 nose: 1.3.7 pip: 9.0.0 setuptools: 28.7.1 Cython: 0.25.1 numpy: 1.11.2 scipy: None statsmodels: None xarray: None IPython: 5.1.0 sphinx: None patsy: None dateutil: 2.5.3 pytz: 2016.7 blosc: None bottleneck: None tables: None numexpr: None matplotlib: None openpyxl: None xlrd: None xlwt: None xlsxwriter: None lxml: None bs4: None html5lib: None httplib2: None apiclient: None sqlalchemy: None pymysql: None psycopg2: None jinja2: None boto: None pandas_datareader: None

Comment From: jreback

duplicate

Comment From: jeanmn

@jreback Issue link? I was on the verge of submitting a pull request to fix this

Comment From: jreback

https://github.com/pandas-dev/pandas/issues/14440 as u indicated

pr are welcome for this (it's an issue duplicate)

Comment From: jeanmn

@jreback I see, thank you for the clarification. I just wanted to make clear that this is a similar issue but at a different location in the code due to duplication of internal rounding logic. I wouldn't be surprised if the same error is found in more locations. FYI: The current affected classes (so far) are Timestamp, Timedelta and DatetimeIndex