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	$220.94	5.529%	$233.1558	$233.16	$233.15	$233.20
Purchase #2	$186.76	4.697%	$195.5321	$195.53	$195.55	$195.50
Purchase #3	$45.59	10.529%	$50.3902	$50.39	$50.40	$50.40
Purchase #4	$140.25	3.695%	$145.4322	$145.43	$145.45	$145.40
Purchase #5	$121.90	10.433%	$134.6178	$134.62	$134.60	$134.60
Purchase #6	$136.82	5.629%	$144.5216	$144.52	$144.50	$144.50
Purchase #7	$109.70	12.854%	$123.8008	$123.80	$123.80	$123.80
7 purchase totals =	$961.96		$1,027.4505	$1,027.45	$1,027.45	$1,027.40