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	$197.42	4.179%	$205.6702	$205.67	$205.65	$205.70
Purchase #2	$249.73	12.546%	$281.0611	$281.06	$281.05	$281.10
Purchase #3	$111.68	5.744%	$118.0949	$118.09	$118.10	$118.10
Purchase #4	$236.36	8.535%	$256.5333	$256.53	$256.55	$256.50
Purchase #5	$240.62	9.476%	$263.4212	$263.42	$263.40	$263.40
Purchase #6	$104.39	6.861%	$111.5522	$111.55	$111.55	$111.60
Purchase #7	$57.96	12.610%	$65.2688	$65.27	$65.25	$65.30
7 purchase totals =	$1,198.16		$1,301.6017	$1,301.59	$1,301.55	$1,301.70