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	$140.77	4.367%	$146.9174	$146.92	$146.90	$146.90
Purchase #2	$104.51	7.414%	$112.2584	$112.26	$112.25	$112.30
Purchase #3	$6.75	7.139%	$7.2319	$7.23	$7.25	$7.20
Purchase #4	$227.31	11.363%	$253.1392	$253.14	$253.15	$253.10
Purchase #5	$202.26	11.274%	$225.0628	$225.06	$225.05	$225.10
Purchase #6	$154.51	8.479%	$167.6109	$167.61	$167.60	$167.60
Purchase #7	$51.30	10.771%	$56.8255	$56.83	$56.85	$56.80
7 purchase totals =	$887.41		$969.0461	$969.05	$969.05	$969.00