BUG:  .corr() values higher than 1
- [x] I have checked that this issue has not already been reported.

- [x] I have confirmed this bug exists on the latest version of pandas.

- [x] (optional) I have confirmed this bug exists on the master branch of pandas.

---

#### Code Sample, a copy-pastable example

_Sorry for including an external dataset. I couldn't reproduce this bug with a smaller one._

```python
url = 'https://raw.githubusercontent.com/MislavSag/trademl/master/trademl/modeling/random_forest/X_TEST.csv'
df = pd.read_csv(url, sep=',')
df = X_TEST.loc[:,['RSI30','CMO30']]

df.corr() > 1
```

#### Problem description

When applying .corr() on the given dataset the output Pearson's correlation is slightly >1 (6.661338e-16). I'd assume it should be equal to 1. 

![picture](https://user-images.githubusercontent.com/16906989/86593669-ed455e00-bf95-11ea-84fe-2a790f894d5e.png)

#### Expected Output

The expected result would be correlation values <= 1.

![picture](https://user-images.githubusercontent.com/16906989/86593787-2d0c4580-bf96-11ea-8358-60b6f5aec462.png)


#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS
------------------
commit           : None
python           : 3.7.7.final.0
python-bits      : 64
OS               : Windows
OS-release       : 10
machine          : AMD64
processor        : Intel64 Family 6 Model 158 Stepping 9, GenuineIntel
byteorder        : little
LC_ALL           : None
LANG             : None
LOCALE           : None.None

pandas           : 1.0.5
numpy            : 1.18.5
pytz             : 2020.1
dateutil         : 2.8.1
pip              : 20.1.1
setuptools       : 47.3.0.post20200616
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : 3.1.1
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : 2.11.2
IPython          : 7.15.0
pandas_datareader: None
bs4              : None
bottleneck       : None
fastparquet      : None
gcsfs            : None
lxml.etree       : None
matplotlib       : 3.2.1
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pytables         : None
pytest           : None
pyxlsb           : None
s3fs             : None
scipy            : 1.4.1
sqlalchemy       : None
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
xlsxwriter       : None
numba            : 0.49.1

</details>
