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	$13.83	5.739%	$14.6237	$14.62	$14.60	$14.60
Purchase #2	$103.98	7.298%	$111.5685	$111.57	$111.55	$111.60
Purchase #3	$203.34	12.711%	$229.1865	$229.19	$229.20	$229.20
Purchase #4	$53.63	12.138%	$60.1396	$60.14	$60.15	$60.10
Purchase #5	$159.45	3.574%	$165.1487	$165.15	$165.15	$165.10
Purchase #6	$72.69	8.871%	$79.1383	$79.14	$79.15	$79.10
Purchase #7	$55.49	13.442%	$62.949	$62.95	$62.95	$62.90
7 purchase totals =	$662.41		$722.7543	$722.76	$722.75	$722.60