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	$100.59	5.450%	$106.0722	$106.07	$106.05	$106.10
Purchase #2	$186.67	10.156%	$205.6282	$205.63	$205.65	$205.60
Purchase #3	$54.89	11.151%	$61.0108	$61.01	$61.00	$61.00
Purchase #4	$109.26	8.167%	$118.1833	$118.18	$118.20	$118.20
Purchase #5	$90.63	8.385%	$98.2293	$98.23	$98.25	$98.20
Purchase #6	$231.90	8.788%	$252.2794	$252.28	$252.30	$252.30
Purchase #7	$166.90	5.109%	$175.4269	$175.43	$175.45	$175.40
7 purchase totals =	$940.84		$1,016.8301	$1,016.83	$1,016.90	$1,016.80