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	$243.62	7.655%	$262.2691	$262.27	$262.25	$262.30
Purchase #2	$63.68	13.695%	$72.401	$72.40	$72.40	$72.40
Purchase #3	$161.87	11.712%	$180.8282	$180.83	$180.85	$180.80
Purchase #4	$47.31	13.458%	$53.677	$53.68	$53.70	$53.70
Purchase #5	$105.47	13.281%	$119.4775	$119.48	$119.50	$119.50
Purchase #6	$28.98	11.413%	$32.2875	$32.29	$32.30	$32.30
Purchase #7	$207.60	5.536%	$219.0927	$219.09	$219.10	$219.10
7 purchase totals =	$858.53		$940.0330	$940.04	$940.10	$940.10