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	$182.87	9.548%	$200.3304	$200.33	$200.35	$200.30
Purchase #2	$56.61	8.670%	$61.5181	$61.52	$61.50	$61.50
Purchase #3	$115.28	11.389%	$128.4092	$128.41	$128.40	$128.40
Purchase #4	$202.62	11.314%	$225.5444	$225.54	$225.55	$225.50
Purchase #5	$46.62	3.588%	$48.2927	$48.29	$48.30	$48.30
Purchase #6	$30.37	13.287%	$34.4053	$34.41	$34.40	$34.40
Purchase #7	$35.84	10.299%	$39.5312	$39.53	$39.55	$39.50
7 purchase totals =	$670.21		$738.0313	$738.03	$738.05	$737.90