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	$179.90	5.655%	$190.0733	$190.07	$190.05	$190.10
Purchase #2	$86.60	10.412%	$95.6168	$95.62	$95.60	$95.60
Purchase #3	$61.82	7.430%	$66.4132	$66.41	$66.40	$66.40
Purchase #4	$89.88	7.520%	$96.639	$96.64	$96.65	$96.60
Purchase #5	$115.40	8.612%	$125.3382	$125.34	$125.35	$125.30
Purchase #6	$69.59	4.562%	$72.7647	$72.76	$72.75	$72.80
Purchase #7	$72.56	11.149%	$80.6497	$80.65	$80.65	$80.60
7 purchase totals =	$675.75		$727.4949	$727.49	$727.45	$727.40