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	$111.89	11.792%	$125.0841	$125.08	$125.10	$125.10
Purchase #2	$9.65	11.233%	$10.734	$10.73	$10.75	$10.70
Purchase #3	$232.95	5.831%	$246.5333	$246.53	$246.55	$246.50
Purchase #4	$125.27	5.131%	$131.6976	$131.70	$131.70	$131.70
Purchase #5	$174.85	9.583%	$191.6059	$191.61	$191.60	$191.60
Purchase #6	$84.92	6.786%	$90.6827	$90.68	$90.70	$90.70
Purchase #7	$81.89	9.712%	$89.8432	$89.84	$89.85	$89.80
7 purchase totals =	$821.42		$886.1808	$886.17	$886.25	$886.10