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	$58.92	4.479%	$61.559	$61.56	$61.55	$61.60
Purchase #2	$244.42	8.525%	$265.2568	$265.26	$265.25	$265.30
Purchase #3	$158.60	5.137%	$166.7473	$166.75	$166.75	$166.70
Purchase #4	$61.81	11.712%	$69.0492	$69.05	$69.05	$69.00
Purchase #5	$173.85	4.377%	$181.4594	$181.46	$181.45	$181.50
Purchase #6	$130.28	11.265%	$144.956	$144.96	$144.95	$145.00
Purchase #7	$237.45	13.384%	$269.2303	$269.23	$269.25	$269.20
7 purchase totals =	$1,065.33		$1,158.2580	$1,158.27	$1,158.25	$1,158.30