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	$160.73	9.480%	$175.9672	$175.97	$175.95	$176.00
Purchase #2	$75.72	9.553%	$82.9535	$82.95	$82.95	$83.00
Purchase #3	$138.89	13.444%	$157.5624	$157.56	$157.55	$157.60
Purchase #4	$188.33	11.225%	$209.47	$209.47	$209.45	$209.50
Purchase #5	$46.83	4.324%	$48.8549	$48.85	$48.85	$48.90
Purchase #6	$101.78	3.382%	$105.2222	$105.22	$105.20	$105.20
Purchase #7	$225.65	11.596%	$251.8164	$251.82	$251.80	$251.80
7 purchase totals =	$937.93		$1,031.8466	$1,031.84	$1,031.75	$1,032.00