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	$182.85	3.717%	$189.6465	$189.65	$189.65	$189.60
Purchase #2	$135.52	7.661%	$145.9022	$145.90	$145.90	$145.90
Purchase #3	$198.89	7.828%	$214.4591	$214.46	$214.45	$214.50
Purchase #4	$127.89	11.585%	$142.7061	$142.71	$142.70	$142.70
Purchase #5	$135.81	9.262%	$148.3887	$148.39	$148.40	$148.40
Purchase #6	$107.48	3.818%	$111.5836	$111.58	$111.60	$111.60
Purchase #7	$196.77	6.555%	$209.6683	$209.67	$209.65	$209.70
7 purchase totals =	$1,085.21		$1,162.3545	$1,162.36	$1,162.35	$1,162.40