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	$192.61	8.444%	$208.874	$208.87	$208.85	$208.90
Purchase #2	$18.95	10.160%	$20.8753	$20.88	$20.90	$20.90
Purchase #3	$30.83	9.211%	$33.6698	$33.67	$33.65	$33.70
Purchase #4	$116.41	5.873%	$123.2468	$123.25	$123.25	$123.20
Purchase #5	$91.32	9.432%	$99.9333	$99.93	$99.95	$99.90
Purchase #6	$157.99	7.738%	$170.2153	$170.22	$170.20	$170.20
Purchase #7	$14.78	5.731%	$15.627	$15.63	$15.65	$15.60
7 purchase totals =	$622.89		$672.4415	$672.45	$672.45	$672.40