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	$96.28	8.468%	$104.433	$104.43	$104.45	$104.40
Purchase #2	$129.51	13.133%	$146.5185	$146.52	$146.50	$146.50
Purchase #3	$171.88	7.405%	$184.6077	$184.61	$184.60	$184.60
Purchase #4	$196.85	6.491%	$209.6275	$209.63	$209.65	$209.60
Purchase #5	$190.40	8.318%	$206.2375	$206.24	$206.25	$206.20
Purchase #6	$38.35	5.545%	$40.4765	$40.48	$40.50	$40.50
Purchase #7	$193.82	13.136%	$219.2802	$219.28	$219.30	$219.30
7 purchase totals =	$1,017.09		$1,111.1809	$1,111.19	$1,111.25	$1,111.10