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	$118.60	7.657%	$127.6812	$127.68	$127.70	$127.70
Purchase #2	$136.39	8.375%	$147.8127	$147.81	$147.80	$147.80
Purchase #3	$148.76	12.509%	$167.3684	$167.37	$167.35	$167.40
Purchase #4	$217.97	3.375%	$225.3265	$225.33	$225.35	$225.30
Purchase #5	$196.89	7.506%	$211.6686	$211.67	$211.65	$211.70
Purchase #6	$196.50	9.707%	$215.5743	$215.57	$215.55	$215.60
Purchase #7	$46.69	10.307%	$51.5023	$51.50	$51.50	$51.50
7 purchase totals =	$1,061.80		$1,146.9340	$1,146.93	$1,146.90	$1,147.00