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	$94.71	9.165%	$103.3902	$103.39	$103.40	$103.40
Purchase #2	$213.64	13.149%	$241.7315	$241.73	$241.75	$241.70
Purchase #3	$161.46	10.772%	$178.8525	$178.85	$178.85	$178.90
Purchase #4	$111.38	8.462%	$120.805	$120.81	$120.80	$120.80
Purchase #5	$136.70	10.824%	$151.4964	$151.50	$151.50	$151.50
Purchase #6	$135.58	8.530%	$147.145	$147.15	$147.15	$147.10
Purchase #7	$113.27	5.199%	$119.1589	$119.16	$119.15	$119.20
7 purchase totals =	$966.74		$1,062.5795	$1,062.59	$1,062.60	$1,062.60