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	$196.27	11.730%	$219.2925	$219.29	$219.30	$219.30
Purchase #2	$196.35	10.548%	$217.061	$217.06	$217.05	$217.10
Purchase #3	$9.80	9.782%	$10.7586	$10.76	$10.75	$10.80
Purchase #4	$49.37	11.495%	$55.0451	$55.05	$55.05	$55.00
Purchase #5	$217.44	12.734%	$245.1288	$245.13	$245.15	$245.10
Purchase #6	$113.84	11.772%	$127.2412	$127.24	$127.25	$127.20
Purchase #7	$104.85	4.464%	$109.5305	$109.53	$109.55	$109.50
7 purchase totals =	$887.92		$984.0577	$984.06	$984.10	$984.00