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	$172.33	13.811%	$196.1305	$196.13	$196.15	$196.10
Purchase #2	$13.96	13.841%	$15.8922	$15.89	$15.90	$15.90
Purchase #3	$28.25	3.295%	$29.1808	$29.18	$29.20	$29.20
Purchase #4	$191.65	11.521%	$213.73	$213.73	$213.75	$213.70
Purchase #5	$150.27	12.179%	$168.5714	$168.57	$168.55	$168.60
Purchase #6	$13.47	8.605%	$14.6291	$14.63	$14.65	$14.60
Purchase #7	$71.75	6.381%	$76.3284	$76.33	$76.35	$76.30
7 purchase totals =	$641.68		$714.4624	$714.46	$714.55	$714.40