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	$239.53	9.504%	$262.2949	$262.29	$262.30	$262.30
Purchase #2	$13.32	4.144%	$13.872	$13.87	$13.85	$13.90
Purchase #3	$245.98	7.594%	$264.6597	$264.66	$264.65	$264.70
Purchase #4	$41.83	10.738%	$46.3217	$46.32	$46.30	$46.30
Purchase #5	$48.38	3.505%	$50.0757	$50.08	$50.10	$50.10
Purchase #6	$17.91	9.712%	$19.6494	$19.65	$19.65	$19.60
Purchase #7	$120.98	5.521%	$127.6593	$127.66	$127.65	$127.70
7 purchase totals =	$727.93		$784.5327	$784.53	$784.50	$784.60