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	$128.45	11.525%	$143.2539	$143.25	$143.25	$143.30
Purchase #2	$216.90	7.656%	$233.5059	$233.51	$233.50	$233.50
Purchase #3	$214.99	7.814%	$231.7893	$231.79	$231.80	$231.80
Purchase #4	$59.30	7.566%	$63.7866	$63.79	$63.80	$63.80
Purchase #5	$122.99	7.553%	$132.2794	$132.28	$132.30	$132.30
Purchase #6	$112.95	9.186%	$123.3256	$123.33	$123.35	$123.30
Purchase #7	$241.37	11.241%	$268.5024	$268.50	$268.50	$268.50
7 purchase totals =	$1,096.95		$1,196.4431	$1,196.45	$1,196.50	$1,196.50