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	$205.59	8.729%	$223.536	$223.54	$223.55	$223.50
Purchase #2	$85.56	12.167%	$95.9701	$95.97	$95.95	$96.00
Purchase #3	$181.49	10.361%	$200.2942	$200.29	$200.30	$200.30
Purchase #4	$180.65	3.564%	$187.0884	$187.09	$187.10	$187.10
Purchase #5	$78.27	9.839%	$85.971	$85.97	$85.95	$86.00
Purchase #6	$135.47	6.683%	$144.5235	$144.52	$144.50	$144.50
Purchase #7	$69.53	3.803%	$72.1742	$72.17	$72.15	$72.20
7 purchase totals =	$936.56		$1,009.5574	$1,009.55	$1,009.50	$1,009.60