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	$59.55	7.245%	$63.8644	$63.86	$63.85	$63.90
Purchase #2	$77.52	10.552%	$85.6999	$85.70	$85.70	$85.70
Purchase #3	$104.69	6.191%	$111.1714	$111.17	$111.15	$111.20
Purchase #4	$18.80	8.779%	$20.4505	$20.45	$20.45	$20.50
Purchase #5	$112.33	4.274%	$117.131	$117.13	$117.15	$117.10
Purchase #6	$214.71	9.611%	$235.3458	$235.35	$235.35	$235.30
Purchase #7	$107.91	6.271%	$114.677	$114.68	$114.70	$114.70
7 purchase totals =	$695.51		$748.3400	$748.34	$748.35	$748.40