Use same rounding logic between Rewards panels and Ads panel

[dodieboy]

Description

The estimated earning found earning found in brave://rewards/ show to different value. Most likely cause by the different rounding off method use

Actual result:

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Brave | 1.33.106 Chromium: 96.0.4664.110 (Official Build) (64-bit)
Revision | d5ef0e8214bc14c9b5bbf69a1515e431394c62a6-refs/branch-heads/4664@{#1283}
OS | Windows 10 Version 21H2 (Build 19044.1348)

[zenparsing]

Note that floating point rounding can differ between Intl.NumberFormat and Number.prototype.toFixed. (See examples at here.)

[stephendonner]

Verified PASSED using

Brave	1.36.47 Chromium: 97.0.4692.71 (Official Build) nightly (x86_64)
Revision	adefa7837d02a07a604c1e6eff0b3a09422ab88d-refs/branch-heads/4692@{#1247}
OS	macOS Version 11.6.1 (Build 20G224)

Steps:

1. new profile
2. clicked on Skip welcome tour
3. clicked on Start using Rewards
4. changed 5 ads per hour to 10 ads per hour on brave://rewards/
5. waited for 1st ad
6. opened brave://rewards
7. checked that the Current earnings this month (estimated) and Estimated Earnings match up
8. repeated steps 5-7 for ads 2-15

Confirmed that both estimated earnings numbers matched and are rounded

1	2	3	4	5	6	7	8

9	10	11	12	13	14	15

NOTE: I also checked the new-tab page widget; just didn't screenshot it each time 👍

---

Verified with

Brave	1.36.93 Chromium: 98.0.4758.87 (Official Build) beta (64-bit) 
Revision	e4cd00f135fb4d8edc64c8aa6ecbe7cc79ebb3b2-refs/branch-heads/4758@{#1002}
OS	Linux

1. new profile
2. clicked on Skip welcome tour
3. clicked on Start using Rewards
4. changed 5 ads per hour to 10 ads per hour on brave://rewards/
5. waited for 1st ad
6. opened brave://rewards
7. checked that the Current earnings this month (estimated) and Estimated Earnings match up
8. repeated steps 5-7 for additional ads

Example	Example	Example

Additionally, modified ad value in DB to ensure rounding was invoked.
Confirmed that rounded value was shown on brave://rewards, on panel, and on NTP widget.

Example	Example

Verified PASSED using

Brave | 1.36.90 Chromium: 98.0.4758.87 (Official Build) beta (64-bit)
Revision | e4cd00f135fb4d8edc64c8aa6ecbe7cc79ebb3b2-refs/branch-heads/4758@{#1002}
OS | Windows 11 Version 21H2 (Build 22000.493)

New profile
Launch brave browser
clicked on Skip welcome tour
clicked on Start using Rewards
waited for 1st ad
opened brave://rewards
Verified that the Current earnings this month (estimated) and Estimated Earnings match up
changed 5 ads per hour to 10 ads per hour on brave://rewards/
Waited for ads 2-5
Opened brave://rewards
Verified Current earnings this month (estimated) and Estimated Earnings match up for Ads 2-5
Switched location "State level ad targeting" = CA
Waited for ads 6-15
Opened brave://rewards
Verified Current earnings this month (estimated) and Estimated Earnings match up for Ads 6-15

1	2	3	4	5	6	7	8	9

11	12	13	14

Brave | 1.37.46 Chromium: 98.0.4758.87 (Official Build) nightly (64-bit)
Revision | e4cd00f135fb4d8edc64c8aa6ecbe7cc79ebb3b2-refs/branch-heads/4758@{#1002}
OS | Windows 11 Version 21H2 (Build 22000.493)

New profile
Launch brave browser (Nightly)
clicked on Skip welcome tour
Enabled rewards
waited for 1st ad
opened brave://rewards
Verified that the Current earnings this month (estimated) and Estimated Earnings match up
changed 5 ads per hour to 10 ads per hour on brave://rewards/
Waited for ads 2-5
Opened brave://rewards
Veried Current earnings this month (estimated) and Estimated Earnings match up for Ads 2-5
Switched location "State level ad targeting" = CA
Waited for ads 6-15
Opened brave://rewards
Verified Current earnings this month (estimated) and Estimated Earnings match up for Ads 6-15

1	2	3	4	5	6	7	8	9

10	11