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	$166.61	4.348%	$173.8542	$173.85	$173.85	$173.90
Purchase #2	$90.81	5.199%	$95.5312	$95.53	$95.55	$95.50
Purchase #3	$203.25	6.506%	$216.4734	$216.47	$216.45	$216.50
Purchase #4	$45.85	13.108%	$51.86	$51.86	$51.85	$51.90
Purchase #5	$190.25	8.746%	$206.8893	$206.89	$206.90	$206.90
Purchase #6	$221.82	6.594%	$236.4468	$236.45	$236.45	$236.40
Purchase #7	$175.70	8.873%	$191.2899	$191.29	$191.30	$191.30
7 purchase totals =	$1,094.29		$1,172.3448	$1,172.34	$1,172.35	$1,172.40