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	$65.96	9.670%	$72.3383	$72.34	$72.35	$72.30
Purchase #2	$161.51	4.398%	$168.6132	$168.61	$168.60	$168.60
Purchase #3	$134.68	5.750%	$142.4241	$142.42	$142.40	$142.40
Purchase #4	$236.30	6.545%	$251.7658	$251.77	$251.75	$251.80
Purchase #5	$138.42	13.226%	$156.7274	$156.73	$156.75	$156.70
Purchase #6	$126.90	10.680%	$140.4529	$140.45	$140.45	$140.50
Purchase #7	$109.72	9.491%	$120.1335	$120.13	$120.15	$120.10
7 purchase totals =	$973.49		$1,052.4552	$1,052.45	$1,052.45	$1,052.40