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	$216.43	4.251%	$225.6304	$225.63	$225.65	$225.60
Purchase #2	$162.40	4.606%	$169.8801	$169.88	$169.90	$169.90
Purchase #3	$227.71	13.622%	$258.7287	$258.73	$258.75	$258.70
Purchase #4	$228.41	11.260%	$254.129	$254.13	$254.15	$254.10
Purchase #5	$233.39	9.649%	$255.9098	$255.91	$255.90	$255.90
Purchase #6	$10.41	4.653%	$10.8944	$10.89	$10.90	$10.90
Purchase #7	$39.43	3.487%	$40.8049	$40.80	$40.80	$40.80
7 purchase totals =	$1,118.18		$1,215.9773	$1,215.97	$1,216.05	$1,215.90