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	$183.80	3.117%	$189.529	$189.53	$189.55	$189.50
Purchase #2	$12.49	4.155%	$13.009	$13.01	$13.00	$13.00
Purchase #3	$227.86	13.143%	$257.8076	$257.81	$257.80	$257.80
Purchase #4	$250.48	11.501%	$279.2877	$279.29	$279.30	$279.30
Purchase #5	$168.42	13.766%	$191.6047	$191.60	$191.60	$191.60
Purchase #6	$148.66	4.679%	$155.6158	$155.62	$155.60	$155.60
Purchase #7	$104.59	4.727%	$109.534	$109.53	$109.55	$109.50
7 purchase totals =	$1,096.30		$1,196.3878	$1,196.39	$1,196.40	$1,196.30