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	$196.72	7.856%	$212.1743	$212.17	$212.15	$212.20
Purchase #2	$49.54	12.461%	$55.7132	$55.71	$55.70	$55.70
Purchase #3	$88.77	13.287%	$100.5649	$100.56	$100.55	$100.60
Purchase #4	$190.47	6.250%	$202.3744	$202.37	$202.35	$202.40
Purchase #5	$220.90	6.538%	$235.3424	$235.34	$235.35	$235.30
Purchase #6	$177.40	6.737%	$189.3514	$189.35	$189.35	$189.40
Purchase #7	$141.91	10.352%	$156.6005	$156.60	$156.60	$156.60
7 purchase totals =	$1,065.71		$1,152.1211	$1,152.10	$1,152.05	$1,152.20