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	$174.64	6.255%	$185.5637	$185.56	$185.55	$185.60
Purchase #2	$25.86	9.824%	$28.4005	$28.40	$28.40	$28.40
Purchase #3	$145.98	3.233%	$150.6995	$150.70	$150.70	$150.70
Purchase #4	$141.95	5.787%	$150.1646	$150.16	$150.15	$150.20
Purchase #5	$139.48	8.152%	$150.8504	$150.85	$150.85	$150.90
Purchase #6	$221.57	7.458%	$238.0947	$238.09	$238.10	$238.10
Purchase #7	$97.89	8.741%	$106.4466	$106.45	$106.45	$106.40
7 purchase totals =	$947.37		$1,010.2200	$1,010.21	$1,010.20	$1,010.30