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	$181.43	8.344%	$196.5685	$196.57	$196.55	$196.60
Purchase #2	$66.51	8.122%	$71.9119	$71.91	$71.90	$71.90
Purchase #3	$128.89	3.630%	$133.5687	$133.57	$133.55	$133.60
Purchase #4	$154.39	6.575%	$164.5411	$164.54	$164.55	$164.50
Purchase #5	$14.98	12.714%	$16.8846	$16.88	$16.90	$16.90
Purchase #6	$172.66	10.359%	$190.5458	$190.55	$190.55	$190.50
Purchase #7	$46.43	12.454%	$52.2124	$52.21	$52.20	$52.20
7 purchase totals =	$765.29		$826.2330	$826.23	$826.20	$826.20