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	$196.26	6.210%	$208.4477	$208.45	$208.45	$208.40
Purchase #2	$220.62	7.148%	$236.3899	$236.39	$236.40	$236.40
Purchase #3	$22.28	3.494%	$23.0585	$23.06	$23.05	$23.10
Purchase #4	$95.51	5.205%	$100.4813	$100.48	$100.50	$100.50
Purchase #5	$131.35	3.800%	$136.3413	$136.34	$136.35	$136.30
Purchase #6	$135.77	5.308%	$142.9767	$142.98	$143.00	$143.00
Purchase #7	$104.59	6.183%	$111.0568	$111.06	$111.05	$111.10
7 purchase totals =	$906.38		$958.7522	$958.76	$958.80	$958.80