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	$177.72	10.815%	$196.9404	$196.94	$196.95	$196.90
Purchase #2	$188.70	10.373%	$208.2739	$208.27	$208.25	$208.30
Purchase #3	$188.82	10.243%	$208.1608	$208.16	$208.15	$208.20
Purchase #4	$11.68	10.366%	$12.8907	$12.89	$12.90	$12.90
Purchase #5	$172.49	7.543%	$185.5009	$185.50	$185.50	$185.50
Purchase #6	$29.26	11.554%	$32.6407	$32.64	$32.65	$32.60
Purchase #7	$59.64	6.846%	$63.723	$63.72	$63.70	$63.70
7 purchase totals =	$828.31		$908.1304	$908.12	$908.10	$908.10