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	$211.69	4.192%	$220.564	$220.56	$220.55	$220.60
Purchase #2	$69.89	12.244%	$78.4473	$78.45	$78.45	$78.40
Purchase #3	$98.68	4.206%	$102.8305	$102.83	$102.85	$102.80
Purchase #4	$245.95	6.856%	$262.8123	$262.81	$262.80	$262.80
Purchase #5	$11.47	9.476%	$12.5569	$12.56	$12.55	$12.60
Purchase #6	$13.49	12.357%	$15.157	$15.16	$15.15	$15.20
Purchase #7	$10.54	13.406%	$11.953	$11.95	$11.95	$12.00
7 purchase totals =	$661.71		$704.3210	$704.32	$704.30	$704.40