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	$190.59	3.322%	$196.9214	$196.92	$196.90	$196.90
Purchase #2	$105.93	10.605%	$117.1639	$117.16	$117.15	$117.20
Purchase #3	$168.58	13.381%	$191.1377	$191.14	$191.15	$191.10
Purchase #4	$20.49	3.696%	$21.2473	$21.25	$21.25	$21.20
Purchase #5	$20.83	9.103%	$22.7262	$22.73	$22.75	$22.70
Purchase #6	$83.47	6.164%	$88.6151	$88.62	$88.60	$88.60
Purchase #7	$87.87	7.410%	$94.3812	$94.38	$94.40	$94.40
7 purchase totals =	$677.76		$732.1928	$732.20	$732.20	$732.10