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	$92.34	13.538%	$104.841	$104.84	$104.85	$104.80
Purchase #2	$29.86	9.604%	$32.7278	$32.73	$32.75	$32.70
Purchase #3	$6.95	3.821%	$7.2156	$7.22	$7.20	$7.20
Purchase #4	$52.57	12.429%	$59.1039	$59.10	$59.10	$59.10
Purchase #5	$54.39	12.849%	$61.3786	$61.38	$61.40	$61.40
Purchase #6	$50.74	6.644%	$54.1112	$54.11	$54.10	$54.10
Purchase #7	$144.29	5.553%	$152.3024	$152.30	$152.30	$152.30
7 purchase totals =	$431.14		$471.6805	$471.68	$471.70	$471.60