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	$105.35	7.218%	$112.9542	$112.95	$112.95	$113.00
Purchase #2	$161.70	3.599%	$167.5196	$167.52	$167.50	$167.50
Purchase #3	$132.38	7.621%	$142.4687	$142.47	$142.45	$142.50
Purchase #4	$174.25	9.333%	$190.5128	$190.51	$190.50	$190.50
Purchase #5	$188.91	12.699%	$212.8997	$212.90	$212.90	$212.90
Purchase #6	$146.30	13.185%	$165.5897	$165.59	$165.60	$165.60
Purchase #7	$222.29	13.639%	$252.6081	$252.61	$252.60	$252.60
7 purchase totals =	$1,131.18		$1,244.5528	$1,244.55	$1,244.50	$1,244.60