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	$55.55	11.648%	$62.0205	$62.02	$62.00	$62.00
Purchase #2	$5.28	9.449%	$5.7789	$5.78	$5.80	$5.80
Purchase #3	$172.65	7.238%	$185.1464	$185.15	$185.15	$185.10
Purchase #4	$49.90	7.316%	$53.5507	$53.55	$53.55	$53.60
Purchase #5	$33.27	13.691%	$37.825	$37.83	$37.85	$37.80
Purchase #6	$145.46	8.554%	$157.9026	$157.90	$157.90	$157.90
Purchase #7	$98.58	5.177%	$103.6835	$103.68	$103.70	$103.70
7 purchase totals =	$560.69		$605.9076	$605.91	$605.95	$605.90