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	$222.74	7.133%	$238.628	$238.63	$238.65	$238.60
Purchase #2	$25.78	6.152%	$27.366	$27.37	$27.35	$27.40
Purchase #3	$38.27	5.491%	$40.3714	$40.37	$40.35	$40.40
Purchase #4	$55.90	4.345%	$58.3289	$58.33	$58.35	$58.30
Purchase #5	$133.27	10.171%	$146.8249	$146.82	$146.80	$146.80
Purchase #6	$52.98	13.150%	$59.9469	$59.95	$59.95	$59.90
Purchase #7	$151.41	4.147%	$157.689	$157.69	$157.70	$157.70
7 purchase totals =	$680.35		$729.1551	$729.16	$729.15	$729.10