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	$211.52	10.739%	$234.2351	$234.24	$234.25	$234.20
Purchase #2	$81.75	4.746%	$85.6299	$85.63	$85.65	$85.60
Purchase #3	$61.67	10.863%	$68.3692	$68.37	$68.35	$68.40
Purchase #4	$185.44	5.873%	$196.3309	$196.33	$196.35	$196.30
Purchase #5	$242.45	5.390%	$255.5181	$255.52	$255.50	$255.50
Purchase #6	$111.87	4.858%	$117.3046	$117.30	$117.30	$117.30
Purchase #7	$123.65	11.259%	$137.5718	$137.57	$137.55	$137.60
7 purchase totals =	$1,018.35		$1,094.9596	$1,094.96	$1,094.95	$1,094.90