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	$188.27	5.359%	$198.3594	$198.36	$198.35	$198.40
Purchase #2	$22.80	4.614%	$23.852	$23.85	$23.85	$23.90
Purchase #3	$202.38	13.386%	$229.4706	$229.47	$229.45	$229.50
Purchase #4	$186.71	9.761%	$204.9348	$204.93	$204.95	$204.90
Purchase #5	$56.58	5.656%	$59.7802	$59.78	$59.80	$59.80
Purchase #6	$231.28	8.654%	$251.295	$251.30	$251.30	$251.30
Purchase #7	$105.33	7.186%	$112.899	$112.90	$112.90	$112.90
7 purchase totals =	$993.35		$1,080.5910	$1,080.59	$1,080.60	$1,080.70