Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$171.61	9.117%	$187.2557	$187.26	$187.25	$187.30
Purchase #2	$33.43	6.172%	$35.4933	$35.49	$35.50	$35.50
Purchase #3	$61.33	4.483%	$64.0794	$64.08	$64.10	$64.10
Purchase #4	$47.30	9.283%	$51.6909	$51.69	$51.70	$51.70
Purchase #5	$139.65	8.431%	$151.4239	$151.42	$151.40	$151.40
Purchase #6	$90.30	11.568%	$100.7459	$100.75	$100.75	$100.70
Purchase #7	$161.99	4.205%	$168.8017	$168.80	$168.80	$168.80
7 purchase totals =	$705.61		$759.4908	$759.49	$759.50	$759.50