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	$86.70	11.720%	$96.8612	$96.86	$96.85	$96.90
Purchase #2	$233.72	12.291%	$262.4465	$262.45	$262.45	$262.40
Purchase #3	$74.74	11.257%	$83.1535	$83.15	$83.15	$83.20
Purchase #4	$54.83	8.753%	$59.6293	$59.63	$59.65	$59.60
Purchase #5	$225.32	9.627%	$247.0116	$247.01	$247.00	$247.00
Purchase #6	$249.89	10.154%	$275.2638	$275.26	$275.25	$275.30
Purchase #7	$66.55	8.279%	$72.0597	$72.06	$72.05	$72.10
7 purchase totals =	$991.75		$1,096.4256	$1,096.42	$1,096.40	$1,096.50