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	$84.45	13.210%	$95.6058	$95.61	$95.60	$95.60
Purchase #2	$182.93	7.290%	$196.2656	$196.27	$196.25	$196.30
Purchase #3	$80.26	13.506%	$91.0999	$91.10	$91.10	$91.10
Purchase #4	$41.60	4.737%	$43.5706	$43.57	$43.55	$43.60
Purchase #5	$131.70	4.423%	$137.5251	$137.53	$137.55	$137.50
Purchase #6	$173.61	4.298%	$181.0718	$181.07	$181.05	$181.10
Purchase #7	$205.37	5.162%	$215.9712	$215.97	$215.95	$216.00
7 purchase totals =	$899.92		$961.1100	$961.12	$961.05	$961.20