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	$200.89	10.745%	$222.4756	$222.48	$222.50	$222.50
Purchase #2	$175.29	8.490%	$190.1721	$190.17	$190.15	$190.20
Purchase #3	$111.76	5.545%	$117.9571	$117.96	$117.95	$118.00
Purchase #4	$55.85	6.412%	$59.4311	$59.43	$59.45	$59.40
Purchase #5	$168.60	13.679%	$191.6628	$191.66	$191.65	$191.70
Purchase #6	$46.34	7.274%	$49.7108	$49.71	$49.70	$49.70
Purchase #7	$173.69	11.481%	$193.6313	$193.63	$193.65	$193.60
7 purchase totals =	$932.42		$1,025.0408	$1,025.04	$1,025.05	$1,025.10