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	$43.46	7.761%	$46.8329	$46.83	$46.85	$46.80
Purchase #2	$174.29	11.641%	$194.5791	$194.58	$194.60	$194.60
Purchase #3	$131.34	12.689%	$148.0057	$148.01	$148.00	$148.00
Purchase #4	$161.51	3.143%	$166.5863	$166.59	$166.60	$166.60
Purchase #5	$130.68	6.784%	$139.5453	$139.55	$139.55	$139.50
Purchase #6	$186.99	3.261%	$193.0877	$193.09	$193.10	$193.10
Purchase #7	$120.42	6.824%	$128.6375	$128.64	$128.65	$128.60
7 purchase totals =	$948.69		$1,017.2745	$1,017.29	$1,017.35	$1,017.20