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	$222.63	6.284%	$236.6201	$236.62	$236.60	$236.60
Purchase #2	$11.53	6.388%	$12.2665	$12.27	$12.25	$12.30
Purchase #3	$223.66	10.290%	$246.6746	$246.67	$246.65	$246.70
Purchase #4	$238.44	10.557%	$263.6121	$263.61	$263.60	$263.60
Purchase #5	$43.57	12.763%	$49.1308	$49.13	$49.15	$49.10
Purchase #6	$186.40	3.144%	$192.2604	$192.26	$192.25	$192.30
Purchase #7	$172.63	13.781%	$196.4201	$196.42	$196.40	$196.40
7 purchase totals =	$1,098.86		$1,196.9846	$1,196.98	$1,196.90	$1,197.00