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	$12.87	13.353%	$14.5885	$14.59	$14.60	$14.60
Purchase #2	$192.45	4.224%	$200.5791	$200.58	$200.60	$200.60
Purchase #3	$177.85	10.488%	$196.5029	$196.50	$196.50	$196.50
Purchase #4	$224.43	6.252%	$238.4614	$238.46	$238.45	$238.50
Purchase #5	$15.31	12.362%	$17.2026	$17.20	$17.20	$17.20
Purchase #6	$194.82	9.266%	$212.872	$212.87	$212.85	$212.90
Purchase #7	$156.83	3.465%	$162.2642	$162.26	$162.25	$162.30
7 purchase totals =	$974.56		$1,042.4707	$1,042.46	$1,042.45	$1,042.60