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	$95.65	10.345%	$105.545	$105.55	$105.55	$105.50
Purchase #2	$54.53	4.264%	$56.8552	$56.86	$56.85	$56.90
Purchase #3	$214.72	12.600%	$241.7747	$241.77	$241.75	$241.80
Purchase #4	$174.79	8.269%	$189.2434	$189.24	$189.25	$189.20
Purchase #5	$226.58	8.742%	$246.3876	$246.39	$246.40	$246.40
Purchase #6	$35.45	5.859%	$37.527	$37.53	$37.55	$37.50
Purchase #7	$237.50	12.648%	$267.539	$267.54	$267.55	$267.50
7 purchase totals =	$1,039.22		$1,144.8719	$1,144.88	$1,144.90	$1,144.80