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	$144.77	9.698%	$158.8098	$158.81	$158.80	$158.80
Purchase #2	$186.78	5.228%	$196.5449	$196.54	$196.55	$196.50
Purchase #3	$189.69	3.375%	$196.092	$196.09	$196.10	$196.10
Purchase #4	$155.66	6.612%	$165.9522	$165.95	$165.95	$166.00
Purchase #5	$85.51	9.252%	$93.4214	$93.42	$93.40	$93.40
Purchase #6	$207.68	12.215%	$233.0481	$233.05	$233.05	$233.00
Purchase #7	$18.41	3.215%	$19.0019	$19.00	$19.00	$19.00
7 purchase totals =	$988.50		$1,062.8703	$1,062.86	$1,062.85	$1,062.80