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	$59.82	4.373%	$62.4359	$62.44	$62.45	$62.40
Purchase #2	$191.30	13.514%	$217.1523	$217.15	$217.15	$217.20
Purchase #3	$174.58	11.616%	$194.8592	$194.86	$194.85	$194.90
Purchase #4	$144.31	5.706%	$152.5443	$152.54	$152.55	$152.50
Purchase #5	$240.77	6.332%	$256.0156	$256.02	$256.00	$256.00
Purchase #6	$196.98	10.807%	$218.2676	$218.27	$218.25	$218.30
Purchase #7	$122.78	9.164%	$134.0316	$134.03	$134.05	$134.00
7 purchase totals =	$1,130.54		$1,235.3065	$1,235.31	$1,235.30	$1,235.30