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	$208.63	4.709%	$218.4544	$218.45	$218.45	$218.50
Purchase #2	$71.40	4.201%	$74.3995	$74.40	$74.40	$74.40
Purchase #3	$90.49	5.674%	$95.6244	$95.62	$95.60	$95.60
Purchase #4	$79.84	13.564%	$90.6695	$90.67	$90.65	$90.70
Purchase #5	$180.52	5.618%	$190.6616	$190.66	$190.65	$190.70
Purchase #6	$212.33	9.773%	$233.081	$233.08	$233.10	$233.10
Purchase #7	$132.70	11.273%	$147.6593	$147.66	$147.65	$147.70
7 purchase totals =	$975.91		$1,050.5497	$1,050.54	$1,050.50	$1,050.70