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	$81.63	7.271%	$87.5653	$87.57	$87.55	$87.60
Purchase #2	$124.92	6.247%	$132.7238	$132.72	$132.70	$132.70
Purchase #3	$197.66	11.562%	$220.5134	$220.51	$220.50	$220.50
Purchase #4	$105.43	5.594%	$111.3278	$111.33	$111.35	$111.30
Purchase #5	$212.44	7.817%	$229.0464	$229.05	$229.05	$229.00
Purchase #6	$179.39	7.512%	$192.8658	$192.87	$192.85	$192.90
Purchase #7	$197.82	12.453%	$222.4545	$222.45	$222.45	$222.50
7 purchase totals =	$1,099.29		$1,196.4970	$1,196.50	$1,196.45	$1,196.50