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	$113.43	5.398%	$119.553	$119.55	$119.55	$119.60
Purchase #2	$203.59	8.578%	$221.054	$221.05	$221.05	$221.10
Purchase #3	$214.53	6.573%	$228.6311	$228.63	$228.65	$228.60
Purchase #4	$212.72	4.422%	$222.1265	$222.13	$222.15	$222.10
Purchase #5	$111.84	3.250%	$115.4748	$115.47	$115.45	$115.50
Purchase #6	$141.76	7.688%	$152.6585	$152.66	$152.65	$152.70
Purchase #7	$71.47	8.219%	$77.3441	$77.34	$77.35	$77.30
7 purchase totals =	$1,069.34		$1,136.8420	$1,136.83	$1,136.85	$1,136.90