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	$81.36	5.743%	$86.0325	$86.03	$86.05	$86.00
Purchase #2	$144.28	4.307%	$150.4941	$150.49	$150.50	$150.50
Purchase #3	$188.35	10.555%	$208.2303	$208.23	$208.25	$208.20
Purchase #4	$46.58	12.122%	$52.2264	$52.23	$52.25	$52.20
Purchase #5	$90.94	11.710%	$101.5891	$101.59	$101.60	$101.60
Purchase #6	$57.47	3.328%	$59.3826	$59.38	$59.40	$59.40
Purchase #7	$184.84	13.323%	$209.4662	$209.47	$209.45	$209.50
7 purchase totals =	$793.82		$867.4212	$867.42	$867.50	$867.40