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	$85.78	10.550%	$94.8298	$94.83	$94.85	$94.80
Purchase #2	$137.51	11.408%	$153.1971	$153.20	$153.20	$153.20
Purchase #3	$92.88	13.161%	$105.1039	$105.10	$105.10	$105.10
Purchase #4	$186.57	13.310%	$211.4025	$211.40	$211.40	$211.40
Purchase #5	$44.38	4.514%	$46.3833	$46.38	$46.40	$46.40
Purchase #6	$40.31	6.567%	$42.9572	$42.96	$42.95	$43.00
Purchase #7	$250.76	9.457%	$274.4744	$274.47	$274.45	$274.50
7 purchase totals =	$838.19		$928.3482	$928.34	$928.35	$928.40