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	$162.85	7.424%	$174.94	$174.94	$174.95	$174.90
Purchase #2	$87.88	13.630%	$99.858	$99.86	$99.85	$99.90
Purchase #3	$248.99	6.590%	$265.3984	$265.40	$265.40	$265.40
Purchase #4	$154.86	3.565%	$160.3808	$160.38	$160.40	$160.40
Purchase #5	$61.39	9.853%	$67.4388	$67.44	$67.45	$67.40
Purchase #6	$119.73	7.304%	$128.4751	$128.48	$128.50	$128.50
Purchase #7	$217.47	10.171%	$239.5889	$239.59	$239.60	$239.60
7 purchase totals =	$1,053.17		$1,136.0800	$1,136.09	$1,136.15	$1,136.10