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	$103.45	9.717%	$113.5022	$113.50	$113.50	$113.50
Purchase #2	$248.54	13.269%	$281.5188	$281.52	$281.50	$281.50
Purchase #3	$24.76	3.687%	$25.6729	$25.67	$25.65	$25.70
Purchase #4	$153.42	11.216%	$170.6276	$170.63	$170.65	$170.60
Purchase #5	$164.85	5.486%	$173.8937	$173.89	$173.90	$173.90
Purchase #6	$37.54	8.301%	$40.6562	$40.66	$40.65	$40.70
Purchase #7	$207.46	11.531%	$231.3822	$231.38	$231.40	$231.40
7 purchase totals =	$940.02		$1,037.2536	$1,037.25	$1,037.25	$1,037.30