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	$130.95	8.565%	$142.1659	$142.17	$142.15	$142.20
Purchase #2	$19.89	10.271%	$21.9329	$21.93	$21.95	$21.90
Purchase #3	$159.98	9.798%	$175.6548	$175.65	$175.65	$175.70
Purchase #4	$85.29	5.433%	$89.9238	$89.92	$89.90	$89.90
Purchase #5	$54.90	5.116%	$57.7087	$57.71	$57.70	$57.70
Purchase #6	$204.34	5.461%	$215.499	$215.50	$215.50	$215.50
Purchase #7	$211.94	5.608%	$223.8256	$223.83	$223.85	$223.80
7 purchase totals =	$867.29		$926.7107	$926.71	$926.70	$926.70