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	$207.48	8.502%	$225.1199	$225.12	$225.10	$225.10
Purchase #2	$119.55	4.199%	$124.5699	$124.57	$124.55	$124.60
Purchase #3	$134.64	5.362%	$141.8594	$141.86	$141.85	$141.90
Purchase #4	$31.60	6.150%	$33.5434	$33.54	$33.55	$33.50
Purchase #5	$238.87	6.806%	$255.1275	$255.13	$255.15	$255.10
Purchase #6	$111.76	13.222%	$126.5369	$126.54	$126.55	$126.50
Purchase #7	$140.66	9.812%	$154.4616	$154.46	$154.45	$154.50
7 purchase totals =	$984.56		$1,061.2186	$1,061.22	$1,061.20	$1,061.20