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	$97.82	10.568%	$108.1576	$108.16	$108.15	$108.20
Purchase #2	$121.98	6.618%	$130.0526	$130.05	$130.05	$130.10
Purchase #3	$137.93	5.349%	$145.3079	$145.31	$145.30	$145.30
Purchase #4	$169.53	3.605%	$175.6416	$175.64	$175.65	$175.60
Purchase #5	$9.61	5.568%	$10.1451	$10.15	$10.15	$10.10
Purchase #6	$55.54	6.587%	$59.1984	$59.20	$59.20	$59.20
Purchase #7	$94.64	11.757%	$105.7668	$105.77	$105.75	$105.80
7 purchase totals =	$687.05		$734.2700	$734.28	$734.25	$734.30