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	$33.83	4.208%	$35.2536	$35.25	$35.25	$35.30
Purchase #2	$107.38	11.147%	$119.3496	$119.35	$119.35	$119.30
Purchase #3	$54.76	11.735%	$61.1861	$61.19	$61.20	$61.20
Purchase #4	$228.70	7.445%	$245.7267	$245.73	$245.75	$245.70
Purchase #5	$243.72	4.169%	$253.8807	$253.88	$253.90	$253.90
Purchase #6	$242.35	12.142%	$271.7761	$271.78	$271.80	$271.80
Purchase #7	$62.81	12.387%	$70.5903	$70.59	$70.60	$70.60
7 purchase totals =	$973.55		$1,057.7631	$1,057.77	$1,057.85	$1,057.80