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	$172.95	13.553%	$196.3899	$196.39	$196.40	$196.40
Purchase #2	$208.66	4.646%	$218.3543	$218.35	$218.35	$218.40
Purchase #3	$32.47	6.322%	$34.5228	$34.52	$34.50	$34.50
Purchase #4	$241.45	9.717%	$264.9117	$264.91	$264.90	$264.90
Purchase #5	$85.97	4.749%	$90.0527	$90.05	$90.05	$90.10
Purchase #6	$164.46	4.695%	$172.1814	$172.18	$172.20	$172.20
Purchase #7	$167.86	4.255%	$175.0024	$175.00	$175.00	$175.00
7 purchase totals =	$1,073.82		$1,151.4152	$1,151.40	$1,151.40	$1,151.50