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	$100.51	7.505%	$108.0533	$108.05	$108.05	$108.10
Purchase #2	$114.34	11.475%	$127.4605	$127.46	$127.45	$127.50
Purchase #3	$69.68	4.225%	$72.624	$72.62	$72.60	$72.60
Purchase #4	$188.78	4.145%	$196.6049	$196.60	$196.60	$196.60
Purchase #5	$138.70	10.689%	$153.5256	$153.53	$153.55	$153.50
Purchase #6	$232.49	6.153%	$246.7951	$246.80	$246.80	$246.80
Purchase #7	$85.76	7.756%	$92.4115	$92.41	$92.40	$92.40
7 purchase totals =	$930.26		$997.4749	$997.47	$997.45	$997.50