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	$215.89	3.310%	$223.036	$223.04	$223.05	$223.00
Purchase #2	$94.65	6.595%	$100.8922	$100.89	$100.90	$100.90
Purchase #3	$41.53	3.591%	$43.0213	$43.02	$43.00	$43.00
Purchase #4	$93.41	8.503%	$101.3527	$101.35	$101.35	$101.40
Purchase #5	$69.42	4.781%	$72.739	$72.74	$72.75	$72.70
Purchase #6	$189.60	5.152%	$199.3682	$199.37	$199.35	$199.40
Purchase #7	$193.93	3.682%	$201.0705	$201.07	$201.05	$201.10
7 purchase totals =	$898.43		$941.4799	$941.48	$941.45	$941.50