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	$215.66	5.332%	$227.159	$227.16	$227.15	$227.20
Purchase #2	$69.82	12.549%	$78.5817	$78.58	$78.60	$78.60
Purchase #3	$153.28	3.299%	$158.3367	$158.34	$158.35	$158.30
Purchase #4	$92.53	13.532%	$105.0512	$105.05	$105.05	$105.10
Purchase #5	$67.42	7.369%	$72.3882	$72.39	$72.40	$72.40
Purchase #6	$205.74	9.360%	$224.9973	$225.00	$225.00	$225.00
Purchase #7	$131.72	5.819%	$139.3848	$139.38	$139.40	$139.40
7 purchase totals =	$936.17		$1,005.8989	$1,005.90	$1,005.95	$1,006.00