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	$125.43	4.779%	$131.4243	$131.42	$131.40	$131.40
Purchase #2	$67.38	3.130%	$69.489	$69.49	$69.50	$69.50
Purchase #3	$54.78	8.201%	$59.2725	$59.27	$59.25	$59.30
Purchase #4	$235.28	8.712%	$255.7776	$255.78	$255.80	$255.80
Purchase #5	$62.88	3.742%	$65.233	$65.23	$65.25	$65.20
Purchase #6	$118.89	6.619%	$126.7593	$126.76	$126.75	$126.80
Purchase #7	$22.94	10.266%	$25.295	$25.30	$25.30	$25.30
7 purchase totals =	$687.58		$733.2507	$733.25	$733.25	$733.30