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	$213.69	5.327%	$225.0733	$225.07	$225.05	$225.10
Purchase #2	$23.28	10.684%	$25.7672	$25.77	$25.75	$25.80
Purchase #3	$151.71	10.852%	$168.1736	$168.17	$168.15	$168.20
Purchase #4	$209.29	4.218%	$218.1179	$218.12	$218.10	$218.10
Purchase #5	$210.59	5.839%	$222.8864	$222.89	$222.90	$222.90
Purchase #6	$136.73	4.755%	$143.2315	$143.23	$143.25	$143.20
Purchase #7	$205.62	12.167%	$230.6378	$230.64	$230.65	$230.60
7 purchase totals =	$1,150.91		$1,233.8877	$1,233.89	$1,233.85	$1,233.90