BUG: cut() precision at the left end does not appear as specified (3 digits by default)
- [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.

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

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**Note**: Please read [this guide](https://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) detailing how to provide the necessary information for us to reproduce your bug.

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

```python
...

bins = 10

df_bins = pd.cut(fatalities_asc.fatality_rate, bins, include_lowest=True)

fatalities_asc['fatality_bin'] = df_bins.values

df_counts = fatalities_asc.groupby('fatality_bin', as_index = False).count()

df_counts

```
You can find the complete code here: 
https://github.com/nnworkspace/covid19-insight/blob/master/covid19-insight.ipynb

#### Problem description

I expected all bounds of the bins appear to be a rounded float with 3 digits of precision. But the output of above code (please pay attention to the first interval, the left bound):

	fatality_bin	Confirmed	Deaths	Recovered	Active	fatality_rate
0	(0.057999999999999996, 1.632]	39	39	39	39	39
1	(1.632, 3.19]	33	33	33	33	33
2	(3.19, 4.748]	27	27	27	27	27
3	(4.748, 6.305]	18	18	18	18	18
4	(6.305, 7.863]	12	12	12	12	12
5	(7.863, 9.421]	2	2	2	2	2
6	(9.421, 10.978]	3	3	3	3	3
7	(10.978, 12.536]	6	6	6	6	6
8	(12.536, 14.094]	2	2	2	2	2
9	(14.094, 15.652]	3	3	3	3	3

When the lower and upper bounds used as labels of a plot, it looks like this (pay attention to the first x-tick label )

![image](https://user-images.githubusercontent.com/8641956/80796334-35639100-8b9f-11ea-97d7-04dc2cc05514.png)


#### Expected Output
(0.058, 1.632] should be the lower bound of the first interval, not an infinite number. 

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

pandas version:  1.0.3

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