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	$132.81	5.750%	$140.4466	$140.45	$140.45	$140.40
Purchase #2	$181.74	13.837%	$206.8874	$206.89	$206.90	$206.90
Purchase #3	$49.75	5.470%	$52.4713	$52.47	$52.45	$52.50
Purchase #4	$191.61	13.310%	$217.1133	$217.11	$217.10	$217.10
Purchase #5	$116.44	10.327%	$128.4648	$128.46	$128.45	$128.50
Purchase #6	$128.33	13.320%	$145.4236	$145.42	$145.40	$145.40
Purchase #7	$186.55	10.509%	$206.1545	$206.15	$206.15	$206.20
7 purchase totals =	$987.23		$1,096.9615	$1,096.95	$1,096.90	$1,097.00