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	$161.39	12.424%	$181.4411	$181.44	$181.45	$181.40
Purchase #2	$129.46	11.384%	$144.1977	$144.20	$144.20	$144.20
Purchase #3	$32.42	5.721%	$34.2747	$34.27	$34.25	$34.30
Purchase #4	$221.61	5.624%	$234.0733	$234.07	$234.05	$234.10
Purchase #5	$214.55	4.133%	$223.4174	$223.42	$223.40	$223.40
Purchase #6	$116.27	13.464%	$131.9246	$131.92	$131.90	$131.90
Purchase #7	$95.51	10.254%	$105.3036	$105.30	$105.30	$105.30
7 purchase totals =	$971.21		$1,054.6324	$1,054.62	$1,054.55	$1,054.60