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	$178.25	7.683%	$191.9449	$191.94	$191.95	$191.90
Purchase #2	$244.48	3.596%	$253.2715	$253.27	$253.25	$253.30
Purchase #3	$149.90	12.261%	$168.2792	$168.28	$168.30	$168.30
Purchase #4	$12.86	12.763%	$14.5013	$14.50	$14.50	$14.50
Purchase #5	$152.46	13.651%	$173.2723	$173.27	$173.25	$173.30
Purchase #6	$87.80	11.628%	$98.0094	$98.01	$98.00	$98.00
Purchase #7	$119.83	3.660%	$124.2158	$124.22	$124.20	$124.20
7 purchase totals =	$945.58		$1,023.4944	$1,023.49	$1,023.45	$1,023.50