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	$98.32	11.376%	$109.5049	$109.50	$109.50	$109.50
Purchase #2	$46.31	9.455%	$50.6886	$50.69	$50.70	$50.70
Purchase #3	$77.26	5.385%	$81.4205	$81.42	$81.40	$81.40
Purchase #4	$103.50	13.482%	$117.4539	$117.45	$117.45	$117.50
Purchase #5	$86.88	4.601%	$90.8773	$90.88	$90.90	$90.90
Purchase #6	$106.68	8.380%	$115.6198	$115.62	$115.60	$115.60
Purchase #7	$52.32	13.598%	$59.4345	$59.43	$59.45	$59.40
7 purchase totals =	$571.27		$624.9995	$624.99	$625.00	$625.00