[BUG] Best sellers wrong currency and without tax

[kkumarcodes]

Describe the bug
In admin panel, the "best sellers" widget on the dashboard always shows dollar currency symbol regardless of the setting. Also, the shown amount does not include tax.

To Reproduce
Steps to reproduce the behavior:

1. Go to admin panel
2. Go to dashboard
3. Look at best sellers widget

Expected behavior
The best seller widget should adhere to currency setting, and also include the relevant tax based on tax category.