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	$41.45	11.281%	$46.126	$46.13	$46.15	$46.10
Purchase #2	$158.69	9.807%	$174.2527	$174.25	$174.25	$174.30
Purchase #3	$41.96	11.343%	$46.7195	$46.72	$46.70	$46.70
Purchase #4	$179.59	9.308%	$196.3062	$196.31	$196.30	$196.30
Purchase #5	$150.99	3.761%	$156.6687	$156.67	$156.65	$156.70
Purchase #6	$247.80	12.777%	$279.4614	$279.46	$279.45	$279.50
Purchase #7	$83.99	5.510%	$88.6178	$88.62	$88.60	$88.60
7 purchase totals =	$904.47		$988.1523	$988.16	$988.10	$988.20