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	$207.49	7.391%	$222.8256	$222.83	$222.85	$222.80
Purchase #2	$10.94	3.272%	$11.298	$11.30	$11.30	$11.30
Purchase #3	$32.82	13.263%	$37.1729	$37.17	$37.15	$37.20
Purchase #4	$112.49	12.320%	$126.3488	$126.35	$126.35	$126.30
Purchase #5	$25.33	11.598%	$28.2678	$28.27	$28.25	$28.30
Purchase #6	$74.33	3.535%	$76.9576	$76.96	$76.95	$77.00
Purchase #7	$233.54	12.395%	$262.4873	$262.49	$262.50	$262.50
7 purchase totals =	$696.94		$765.3580	$765.37	$765.35	$765.40