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	$217.36	4.677%	$227.5259	$227.53	$227.55	$227.50
Purchase #2	$83.70	4.661%	$87.6013	$87.60	$87.60	$87.60
Purchase #3	$84.33	5.698%	$89.1351	$89.14	$89.15	$89.10
Purchase #4	$96.88	8.533%	$105.1468	$105.15	$105.15	$105.10
Purchase #5	$7.61	7.183%	$8.1566	$8.16	$8.15	$8.20
Purchase #6	$80.86	3.597%	$83.7685	$83.77	$83.75	$83.80
Purchase #7	$82.51	4.416%	$86.1536	$86.15	$86.15	$86.20
7 purchase totals =	$653.25		$687.4878	$687.50	$687.50	$687.50