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	$198.59	9.497%	$217.4501	$217.45	$217.45	$217.50
Purchase #2	$77.37	5.368%	$81.5232	$81.52	$81.50	$81.50
Purchase #3	$102.87	3.144%	$106.1042	$106.10	$106.10	$106.10
Purchase #4	$24.87	10.394%	$27.455	$27.46	$27.45	$27.50
Purchase #5	$122.25	7.124%	$130.9591	$130.96	$130.95	$131.00
Purchase #6	$52.90	7.519%	$56.8776	$56.88	$56.90	$56.90
Purchase #7	$143.56	6.321%	$152.6344	$152.63	$152.65	$152.60
7 purchase totals =	$722.41		$773.0036	$773.00	$773.00	$773.10