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	$215.35	4.339%	$224.694	$224.69	$224.70	$224.70
Purchase #2	$55.61	7.148%	$59.585	$59.59	$59.60	$59.60
Purchase #3	$206.70	7.479%	$222.1591	$222.16	$222.15	$222.20
Purchase #4	$16.97	8.760%	$18.4566	$18.46	$18.45	$18.50
Purchase #5	$211.51	6.601%	$225.4718	$225.47	$225.45	$225.50
Purchase #6	$119.87	3.829%	$124.4598	$124.46	$124.45	$124.50
Purchase #7	$93.86	7.182%	$100.601	$100.60	$100.60	$100.60
7 purchase totals =	$919.87		$975.4273	$975.43	$975.40	$975.60