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	$174.39	12.453%	$196.1068	$196.11	$196.10	$196.10
Purchase #2	$164.29	12.816%	$185.3454	$185.35	$185.35	$185.30
Purchase #3	$52.75	5.237%	$55.5125	$55.51	$55.50	$55.50
Purchase #4	$46.41	9.312%	$50.7317	$50.73	$50.75	$50.70
Purchase #5	$199.96	8.827%	$217.6105	$217.61	$217.60	$217.60
Purchase #6	$220.52	12.287%	$247.6153	$247.62	$247.60	$247.60
Purchase #7	$203.92	5.351%	$214.8318	$214.83	$214.85	$214.80
7 purchase totals =	$1,062.24		$1,167.7540	$1,167.76	$1,167.75	$1,167.60