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	$193.99	10.154%	$213.6877	$213.69	$213.70	$213.70
Purchase #2	$58.90	7.146%	$63.109	$63.11	$63.10	$63.10
Purchase #3	$246.83	3.627%	$255.7825	$255.78	$255.80	$255.80
Purchase #4	$43.33	12.529%	$48.7588	$48.76	$48.75	$48.80
Purchase #5	$90.89	8.237%	$98.3766	$98.38	$98.40	$98.40
Purchase #6	$85.54	11.312%	$95.2163	$95.22	$95.20	$95.20
Purchase #7	$101.45	9.842%	$111.4347	$111.43	$111.45	$111.40
7 purchase totals =	$820.93		$886.3656	$886.37	$886.40	$886.40