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	$132.70	5.538%	$140.0489	$140.05	$140.05	$140.00
Purchase #2	$119.92	6.206%	$127.3622	$127.36	$127.35	$127.40
Purchase #3	$168.28	6.412%	$179.0701	$179.07	$179.05	$179.10
Purchase #4	$55.66	6.168%	$59.0931	$59.09	$59.10	$59.10
Purchase #5	$29.76	8.677%	$32.3423	$32.34	$32.35	$32.30
Purchase #6	$35.77	8.489%	$38.8065	$38.81	$38.80	$38.80
Purchase #7	$142.34	4.514%	$148.7652	$148.77	$148.75	$148.80
7 purchase totals =	$684.43		$725.4883	$725.49	$725.45	$725.50