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	$119.53	3.450%	$123.6538	$123.65	$123.65	$123.70
Purchase #2	$127.56	5.164%	$134.1472	$134.15	$134.15	$134.10
Purchase #3	$10.88	5.437%	$11.4715	$11.47	$11.45	$11.50
Purchase #4	$140.61	9.229%	$153.5869	$153.59	$153.60	$153.60
Purchase #5	$18.77	5.336%	$19.7716	$19.77	$19.75	$19.80
Purchase #6	$143.82	11.625%	$160.5391	$160.54	$160.55	$160.50
Purchase #7	$123.56	4.795%	$129.4847	$129.48	$129.50	$129.50
7 purchase totals =	$684.73		$732.6548	$732.65	$732.65	$732.70