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	$60.58	7.675%	$65.2295	$65.23	$65.25	$65.20
Purchase #2	$176.43	9.662%	$193.4767	$193.48	$193.50	$193.50
Purchase #3	$50.43	4.198%	$52.5471	$52.55	$52.55	$52.50
Purchase #4	$17.52	7.831%	$18.892	$18.89	$18.90	$18.90
Purchase #5	$245.94	4.247%	$256.3851	$256.39	$256.40	$256.40
Purchase #6	$23.32	8.861%	$25.3864	$25.39	$25.40	$25.40
Purchase #7	$74.49	11.227%	$82.853	$82.85	$82.85	$82.90
7 purchase totals =	$648.71		$694.7698	$694.78	$694.85	$694.80