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	$180.90	9.703%	$198.4527	$198.45	$198.45	$198.50
Purchase #2	$6.59	13.105%	$7.4536	$7.45	$7.45	$7.50
Purchase #3	$162.39	7.148%	$173.9976	$174.00	$174.00	$174.00
Purchase #4	$222.46	10.496%	$245.8094	$245.81	$245.80	$245.80
Purchase #5	$166.85	11.119%	$185.4021	$185.40	$185.40	$185.40
Purchase #6	$78.42	10.470%	$86.6306	$86.63	$86.65	$86.60
Purchase #7	$50.57	7.509%	$54.3673	$54.37	$54.35	$54.40
7 purchase totals =	$868.18		$952.1133	$952.11	$952.10	$952.20