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	$182.79	8.571%	$198.4569	$198.46	$198.45	$198.50
Purchase #2	$178.28	5.849%	$188.7076	$188.71	$188.70	$188.70
Purchase #3	$163.39	13.409%	$185.299	$185.30	$185.30	$185.30
Purchase #4	$156.43	3.182%	$161.4076	$161.41	$161.40	$161.40
Purchase #5	$193.37	3.169%	$199.4979	$199.50	$199.50	$199.50
Purchase #6	$8.86	5.761%	$9.3704	$9.37	$9.35	$9.40
Purchase #7	$148.32	13.845%	$168.8549	$168.85	$168.85	$168.90
7 purchase totals =	$1,031.44		$1,111.5943	$1,111.60	$1,111.55	$1,111.70