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	$116.90	8.519%	$126.8587	$126.86	$126.85	$126.90
Purchase #2	$181.90	7.820%	$196.1246	$196.12	$196.10	$196.10
Purchase #3	$79.46	7.744%	$85.6134	$85.61	$85.60	$85.60
Purchase #4	$213.37	5.485%	$225.0733	$225.07	$225.05	$225.10
Purchase #5	$204.32	8.462%	$221.6096	$221.61	$221.60	$221.60
Purchase #6	$211.74	3.263%	$218.6491	$218.65	$218.65	$218.60
Purchase #7	$234.45	3.369%	$242.3486	$242.35	$242.35	$242.30
7 purchase totals =	$1,242.14		$1,316.2773	$1,316.27	$1,316.20	$1,316.20