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	$176.48	9.277%	$192.852	$192.85	$192.85	$192.90
Purchase #2	$7.98	6.338%	$8.4858	$8.49	$8.50	$8.50
Purchase #3	$11.80	13.690%	$13.4154	$13.42	$13.40	$13.40
Purchase #4	$176.93	13.561%	$200.9235	$200.92	$200.90	$200.90
Purchase #5	$210.89	3.266%	$217.7777	$217.78	$217.80	$217.80
Purchase #6	$61.56	6.858%	$65.7818	$65.78	$65.80	$65.80
Purchase #7	$113.96	8.751%	$123.9326	$123.93	$123.95	$123.90
7 purchase totals =	$759.60		$823.1688	$823.17	$823.20	$823.20