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	$129.27	9.115%	$141.053	$141.05	$141.05	$141.10
Purchase #2	$53.67	4.589%	$56.1329	$56.13	$56.15	$56.10
Purchase #3	$106.39	5.176%	$111.8967	$111.90	$111.90	$111.90
Purchase #4	$182.70	7.752%	$196.8629	$196.86	$196.85	$196.90
Purchase #5	$94.55	11.342%	$105.2739	$105.27	$105.25	$105.30
Purchase #6	$154.84	9.442%	$169.46	$169.46	$169.45	$169.50
Purchase #7	$186.82	3.521%	$193.3979	$193.40	$193.40	$193.40
7 purchase totals =	$908.24		$974.0773	$974.07	$974.05	$974.20