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	$209.56	8.498%	$227.3684	$227.37	$227.35	$227.40
Purchase #2	$150.44	7.796%	$162.1683	$162.17	$162.15	$162.20
Purchase #3	$248.37	7.195%	$266.2402	$266.24	$266.25	$266.20
Purchase #4	$106.95	5.261%	$112.5766	$112.58	$112.60	$112.60
Purchase #5	$20.71	11.307%	$23.0517	$23.05	$23.05	$23.10
Purchase #6	$96.83	7.804%	$104.3866	$104.39	$104.40	$104.40
Purchase #7	$189.48	13.784%	$215.5979	$215.60	$215.60	$215.60
7 purchase totals =	$1,022.34		$1,111.3897	$1,111.40	$1,111.40	$1,111.50