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	$217.37	7.234%	$233.0945	$233.09	$233.10	$233.10
Purchase #2	$136.51	12.133%	$153.0728	$153.07	$153.05	$153.10
Purchase #3	$52.48	13.123%	$59.367	$59.37	$59.35	$59.40
Purchase #4	$223.27	4.688%	$233.7369	$233.74	$233.75	$233.70
Purchase #5	$152.37	6.677%	$162.5437	$162.54	$162.55	$162.50
Purchase #6	$241.87	3.311%	$249.8783	$249.88	$249.90	$249.90
Purchase #7	$166.80	4.187%	$173.7839	$173.78	$173.80	$173.80
7 purchase totals =	$1,190.67		$1,265.4771	$1,265.47	$1,265.50	$1,265.50