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	$52.67	3.685%	$54.6109	$54.61	$54.60	$54.60
Purchase #2	$176.26	11.318%	$196.2091	$196.21	$196.20	$196.20
Purchase #3	$87.36	10.564%	$96.5887	$96.59	$96.60	$96.60
Purchase #4	$119.99	6.434%	$127.7102	$127.71	$127.70	$127.70
Purchase #5	$212.92	12.686%	$239.931	$239.93	$239.95	$239.90
Purchase #6	$209.67	8.329%	$227.1334	$227.13	$227.15	$227.10
Purchase #7	$68.56	5.531%	$72.3521	$72.35	$72.35	$72.40
7 purchase totals =	$927.43		$1,014.5354	$1,014.53	$1,014.55	$1,014.50