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	$196.77	9.504%	$215.471	$215.47	$215.45	$215.50
Purchase #2	$184.87	7.592%	$198.9053	$198.91	$198.90	$198.90
Purchase #3	$183.78	6.357%	$195.4629	$195.46	$195.45	$195.50
Purchase #4	$96.50	13.837%	$109.8527	$109.85	$109.85	$109.90
Purchase #5	$232.54	13.321%	$263.5167	$263.52	$263.50	$263.50
Purchase #6	$41.83	5.408%	$44.0922	$44.09	$44.10	$44.10
Purchase #7	$48.32	5.474%	$50.965	$50.97	$50.95	$51.00
7 purchase totals =	$984.61		$1,078.2658	$1,078.27	$1,078.20	$1,078.40