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	$110.79	5.607%	$117.002	$117.00	$117.00	$117.00
Purchase #2	$56.33	5.475%	$59.4141	$59.41	$59.40	$59.40
Purchase #3	$158.96	6.734%	$169.6644	$169.66	$169.65	$169.70
Purchase #4	$12.90	13.172%	$14.5992	$14.60	$14.60	$14.60
Purchase #5	$207.38	9.801%	$227.7053	$227.71	$227.70	$227.70
Purchase #6	$105.67	6.430%	$112.4646	$112.46	$112.45	$112.50
Purchase #7	$214.77	6.435%	$228.5904	$228.59	$228.60	$228.60
7 purchase totals =	$866.80		$929.4400	$929.43	$929.40	$929.50