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	$207.89	4.308%	$216.8459	$216.85	$216.85	$216.80
Purchase #2	$54.83	9.354%	$59.9588	$59.96	$59.95	$60.00
Purchase #3	$164.48	6.350%	$174.9245	$174.92	$174.90	$174.90
Purchase #4	$226.80	11.590%	$253.0861	$253.09	$253.10	$253.10
Purchase #5	$155.97	13.795%	$177.4861	$177.49	$177.50	$177.50
Purchase #6	$204.63	8.729%	$222.4922	$222.49	$222.50	$222.50
Purchase #7	$113.77	4.200%	$118.5483	$118.55	$118.55	$118.50
7 purchase totals =	$1,128.37		$1,223.3419	$1,223.35	$1,223.35	$1,223.30