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	$229.50	5.185%	$241.3996	$241.40	$241.40	$241.40
Purchase #2	$12.62	9.470%	$13.8151	$13.82	$13.80	$13.80
Purchase #3	$184.35	13.792%	$209.7756	$209.78	$209.80	$209.80
Purchase #4	$222.83	10.357%	$245.9085	$245.91	$245.90	$245.90
Purchase #5	$24.47	8.344%	$26.5118	$26.51	$26.50	$26.50
Purchase #6	$192.85	13.581%	$219.041	$219.04	$219.05	$219.00
Purchase #7	$182.45	7.614%	$196.3417	$196.34	$196.35	$196.30
7 purchase totals =	$1,049.07		$1,152.7933	$1,152.80	$1,152.80	$1,152.70