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	$184.72	13.115%	$208.946	$208.95	$208.95	$208.90
Purchase #2	$83.73	13.431%	$94.9758	$94.98	$95.00	$95.00
Purchase #3	$51.25	5.542%	$54.0903	$54.09	$54.10	$54.10
Purchase #4	$11.61	3.132%	$11.9736	$11.97	$11.95	$12.00
Purchase #5	$122.51	4.467%	$127.9825	$127.98	$128.00	$128.00
Purchase #6	$85.46	4.239%	$89.0826	$89.08	$89.10	$89.10
Purchase #7	$24.73	4.182%	$25.7642	$25.76	$25.75	$25.80
7 purchase totals =	$564.01		$612.8150	$612.81	$612.85	$612.90