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	$100.74	13.140%	$113.9772	$113.98	$114.00	$114.00
Purchase #2	$214.44	4.768%	$224.6645	$224.66	$224.65	$224.70
Purchase #3	$214.70	4.771%	$224.9433	$224.94	$224.95	$224.90
Purchase #4	$137.74	9.354%	$150.6242	$150.62	$150.60	$150.60
Purchase #5	$36.91	9.640%	$40.4681	$40.47	$40.45	$40.50
Purchase #6	$133.36	13.250%	$151.0302	$151.03	$151.05	$151.00
Purchase #7	$98.34	13.756%	$111.8677	$111.87	$111.85	$111.90
7 purchase totals =	$936.23		$1,017.5752	$1,017.57	$1,017.55	$1,017.60