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	$42.96	8.158%	$46.4647	$46.46	$46.45	$46.50
Purchase #2	$80.40	12.653%	$90.573	$90.57	$90.55	$90.60
Purchase #3	$235.43	8.615%	$255.7123	$255.71	$255.70	$255.70
Purchase #4	$83.87	8.596%	$91.0795	$91.08	$91.10	$91.10
Purchase #5	$128.67	4.743%	$134.7728	$134.77	$134.75	$134.80
Purchase #6	$201.67	6.483%	$214.7443	$214.74	$214.75	$214.70
Purchase #7	$72.85	8.259%	$78.8667	$78.87	$78.85	$78.90
7 purchase totals =	$845.85		$912.2133	$912.20	$912.15	$912.30