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	$180.93	8.357%	$196.0503	$196.05	$196.05	$196.10
Purchase #2	$12.45	8.297%	$13.483	$13.48	$13.50	$13.50
Purchase #3	$90.36	8.872%	$98.3767	$98.38	$98.40	$98.40
Purchase #4	$52.50	4.690%	$54.9623	$54.96	$54.95	$55.00
Purchase #5	$82.26	6.658%	$87.7369	$87.74	$87.75	$87.70
Purchase #6	$108.48	6.492%	$115.5225	$115.52	$115.50	$115.50
Purchase #7	$31.59	13.352%	$35.8079	$35.81	$35.80	$35.80
7 purchase totals =	$558.57		$601.9396	$601.94	$601.95	$602.00