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	$104.39	6.552%	$111.2296	$111.23	$111.25	$111.20
Purchase #2	$15.90	9.838%	$17.4642	$17.46	$17.45	$17.50
Purchase #3	$184.40	6.789%	$196.9189	$196.92	$196.90	$196.90
Purchase #4	$151.39	4.624%	$158.3903	$158.39	$158.40	$158.40
Purchase #5	$191.97	13.357%	$217.6114	$217.61	$217.60	$217.60
Purchase #6	$109.56	4.240%	$114.2053	$114.21	$114.20	$114.20
Purchase #7	$17.32	5.621%	$18.2936	$18.29	$18.30	$18.30
7 purchase totals =	$774.93		$834.1133	$834.11	$834.10	$834.10