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	$174.54	9.445%	$191.0253	$191.03	$191.05	$191.00
Purchase #2	$166.91	11.286%	$185.7475	$185.75	$185.75	$185.70
Purchase #3	$188.95	5.871%	$200.0433	$200.04	$200.05	$200.00
Purchase #4	$124.75	12.485%	$140.325	$140.33	$140.35	$140.30
Purchase #5	$63.39	11.404%	$70.619	$70.62	$70.60	$70.60
Purchase #6	$238.55	8.316%	$258.3878	$258.39	$258.40	$258.40
Purchase #7	$20.70	9.210%	$22.6065	$22.61	$22.60	$22.60
7 purchase totals =	$977.79		$1,068.7544	$1,068.77	$1,068.80	$1,068.60