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	$197.26	4.705%	$206.5411	$206.54	$206.55	$206.50
Purchase #2	$9.60	11.539%	$10.7077	$10.71	$10.70	$10.70
Purchase #3	$237.89	10.373%	$262.5663	$262.57	$262.55	$262.60
Purchase #4	$76.38	10.471%	$84.3777	$84.38	$84.40	$84.40
Purchase #5	$90.97	11.625%	$101.5453	$101.55	$101.55	$101.50
Purchase #6	$91.90	13.730%	$104.5179	$104.52	$104.50	$104.50
Purchase #7	$113.72	11.725%	$127.0537	$127.05	$127.05	$127.10
7 purchase totals =	$817.72		$897.3097	$897.32	$897.30	$897.30