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	$224.27	4.152%	$233.5817	$233.58	$233.60	$233.60
Purchase #2	$226.39	10.412%	$249.9617	$249.96	$249.95	$250.00
Purchase #3	$58.79	12.439%	$66.1029	$66.10	$66.10	$66.10
Purchase #4	$91.45	7.706%	$98.4971	$98.50	$98.50	$98.50
Purchase #5	$207.79	7.388%	$223.1415	$223.14	$223.15	$223.10
Purchase #6	$139.35	8.104%	$150.6429	$150.64	$150.65	$150.60
Purchase #7	$72.72	11.518%	$81.0959	$81.10	$81.10	$81.10
7 purchase totals =	$1,020.76		$1,103.0237	$1,103.02	$1,103.05	$1,103.00