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	$126.38	11.865%	$141.375	$141.38	$141.40	$141.40
Purchase #2	$7.43	8.851%	$8.0876	$8.09	$8.10	$8.10
Purchase #3	$85.25	4.855%	$89.3889	$89.39	$89.40	$89.40
Purchase #4	$37.34	9.494%	$40.8851	$40.89	$40.90	$40.90
Purchase #5	$116.66	4.516%	$121.9284	$121.93	$121.95	$121.90
Purchase #6	$163.92	5.118%	$172.3094	$172.31	$172.30	$172.30
Purchase #7	$163.55	12.862%	$184.5858	$184.59	$184.60	$184.60
7 purchase totals =	$700.53		$758.5602	$758.58	$758.65	$758.60