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	$195.93	10.249%	$216.0109	$216.01	$216.00	$216.00
Purchase #2	$62.75	7.479%	$67.4431	$67.44	$67.45	$67.40
Purchase #3	$31.52	13.805%	$35.8713	$35.87	$35.85	$35.90
Purchase #4	$65.73	10.777%	$72.8137	$72.81	$72.80	$72.80
Purchase #5	$92.73	7.463%	$99.6504	$99.65	$99.65	$99.70
Purchase #6	$47.82	7.611%	$51.4596	$51.46	$51.45	$51.50
Purchase #7	$206.69	12.196%	$231.8979	$231.90	$231.90	$231.90
7 purchase totals =	$703.17		$775.1469	$775.14	$775.10	$775.20