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	$61.68	3.140%	$63.6168	$63.62	$63.60	$63.60
Purchase #2	$6.46	3.519%	$6.6873	$6.69	$6.70	$6.70
Purchase #3	$115.38	10.578%	$127.5849	$127.58	$127.60	$127.60
Purchase #4	$60.64	4.760%	$63.5265	$63.53	$63.55	$63.50
Purchase #5	$160.63	6.683%	$171.3649	$171.36	$171.35	$171.40
Purchase #6	$61.92	5.661%	$65.4253	$65.43	$65.45	$65.40
Purchase #7	$205.29	12.653%	$231.2653	$231.27	$231.25	$231.30
7 purchase totals =	$672.00		$729.4710	$729.48	$729.50	$729.50