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	$173.59	5.370%	$182.9118	$182.91	$182.90	$182.90
Purchase #2	$44.53	3.471%	$46.0756	$46.08	$46.10	$46.10
Purchase #3	$176.54	3.413%	$182.5653	$182.57	$182.55	$182.60
Purchase #4	$21.61	9.152%	$23.5877	$23.59	$23.60	$23.60
Purchase #5	$46.61	8.109%	$50.3896	$50.39	$50.40	$50.40
Purchase #6	$157.49	11.412%	$175.4628	$175.46	$175.45	$175.50
Purchase #7	$56.72	9.788%	$62.2718	$62.27	$62.25	$62.30
7 purchase totals =	$677.09		$723.2646	$723.27	$723.25	$723.40