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	$59.44	4.395%	$62.0524	$62.05	$62.05	$62.10
Purchase #2	$11.75	9.296%	$12.8423	$12.84	$12.85	$12.80
Purchase #3	$164.28	4.648%	$171.9157	$171.92	$171.90	$171.90
Purchase #4	$189.74	5.664%	$200.4869	$200.49	$200.50	$200.50
Purchase #5	$195.54	3.501%	$202.3859	$202.39	$202.40	$202.40
Purchase #6	$108.71	13.666%	$123.5663	$123.57	$123.55	$123.60
Purchase #7	$95.80	10.536%	$105.8935	$105.89	$105.90	$105.90
7 purchase totals =	$825.26		$879.1430	$879.15	$879.15	$879.20