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	$87.61	9.735%	$96.1388	$96.14	$96.15	$96.10
Purchase #2	$63.80	12.729%	$71.9211	$71.92	$71.90	$71.90
Purchase #3	$143.27	10.495%	$158.3062	$158.31	$158.30	$158.30
Purchase #4	$130.83	4.824%	$137.1412	$137.14	$137.15	$137.10
Purchase #5	$60.58	5.307%	$63.795	$63.80	$63.80	$63.80
Purchase #6	$16.64	12.427%	$18.7079	$18.71	$18.70	$18.70
Purchase #7	$159.59	5.504%	$168.3738	$168.37	$168.35	$168.40
7 purchase totals =	$662.32		$714.3840	$714.39	$714.35	$714.30