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	$194.33	10.125%	$214.0059	$214.01	$214.00	$214.00
Purchase #2	$15.27	4.393%	$15.9408	$15.94	$15.95	$15.90
Purchase #3	$97.29	5.601%	$102.7392	$102.74	$102.75	$102.70
Purchase #4	$134.42	10.361%	$148.3473	$148.35	$148.35	$148.30
Purchase #5	$100.71	10.645%	$111.4306	$111.43	$111.45	$111.40
Purchase #6	$194.82	7.573%	$209.5737	$209.57	$209.55	$209.60
Purchase #7	$239.86	13.147%	$271.3944	$271.39	$271.40	$271.40
7 purchase totals =	$976.70		$1,073.4319	$1,073.43	$1,073.45	$1,073.30