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	$116.81	12.677%	$131.618	$131.62	$131.60	$131.60
Purchase #2	$7.32	4.639%	$7.6596	$7.66	$7.65	$7.70
Purchase #3	$166.58	11.572%	$185.8566	$185.86	$185.85	$185.90
Purchase #4	$191.60	8.319%	$207.5392	$207.54	$207.55	$207.50
Purchase #5	$200.37	11.220%	$222.8515	$222.85	$222.85	$222.90
Purchase #6	$96.87	6.240%	$102.9147	$102.91	$102.90	$102.90
Purchase #7	$44.27	5.719%	$46.8018	$46.80	$46.80	$46.80
7 purchase totals =	$823.82		$905.2414	$905.24	$905.20	$905.30