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	$209.95	3.528%	$217.357	$217.36	$217.35	$217.40
Purchase #2	$69.48	12.542%	$78.1942	$78.19	$78.20	$78.20
Purchase #3	$158.54	8.528%	$172.0603	$172.06	$172.05	$172.10
Purchase #4	$224.78	13.150%	$254.3386	$254.34	$254.35	$254.30
Purchase #5	$180.71	13.493%	$205.0932	$205.09	$205.10	$205.10
Purchase #6	$57.34	3.485%	$59.3383	$59.34	$59.35	$59.30
Purchase #7	$212.69	9.636%	$233.1848	$233.18	$233.20	$233.20
7 purchase totals =	$1,113.49		$1,219.5664	$1,219.56	$1,219.60	$1,219.60