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	$92.83	12.478%	$104.4133	$104.41	$104.40	$104.40
Purchase #2	$6.62	4.496%	$6.9176	$6.92	$6.90	$6.90
Purchase #3	$174.80	6.856%	$186.7843	$186.78	$186.80	$186.80
Purchase #4	$19.61	3.792%	$20.3536	$20.35	$20.35	$20.40
Purchase #5	$74.82	12.124%	$83.8912	$83.89	$83.90	$83.90
Purchase #6	$143.54	12.436%	$161.3906	$161.39	$161.40	$161.40
Purchase #7	$45.65	11.487%	$50.8938	$50.89	$50.90	$50.90
7 purchase totals =	$557.87		$614.6444	$614.63	$614.65	$614.70