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	$221.27	5.680%	$233.8381	$233.84	$233.85	$233.80
Purchase #2	$16.29	11.429%	$18.1518	$18.15	$18.15	$18.20
Purchase #3	$108.79	3.816%	$112.9414	$112.94	$112.95	$112.90
Purchase #4	$218.76	11.568%	$244.0662	$244.07	$244.05	$244.10
Purchase #5	$92.91	6.570%	$99.0142	$99.01	$99.00	$99.00
Purchase #6	$123.30	11.473%	$137.4462	$137.45	$137.45	$137.40
Purchase #7	$220.25	9.116%	$240.328	$240.33	$240.35	$240.30
7 purchase totals =	$1,001.57		$1,085.7859	$1,085.79	$1,085.80	$1,085.70