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	$214.89	10.869%	$238.2464	$238.25	$238.25	$238.20
Purchase #2	$203.87	5.148%	$214.3652	$214.37	$214.35	$214.40
Purchase #3	$119.61	11.405%	$133.2515	$133.25	$133.25	$133.30
Purchase #4	$246.52	3.759%	$255.7867	$255.79	$255.80	$255.80
Purchase #5	$14.69	4.552%	$15.3587	$15.36	$15.35	$15.40
Purchase #6	$16.52	11.723%	$18.4566	$18.46	$18.45	$18.50
Purchase #7	$242.39	13.644%	$275.4617	$275.46	$275.45	$275.50
7 purchase totals =	$1,058.49		$1,150.9268	$1,150.94	$1,150.90	$1,151.10