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	$181.62	10.622%	$200.9117	$200.91	$200.90	$200.90
Purchase #2	$250.67	10.428%	$276.8099	$276.81	$276.80	$276.80
Purchase #3	$82.30	12.731%	$92.7776	$92.78	$92.80	$92.80
Purchase #4	$176.85	11.188%	$196.636	$196.64	$196.65	$196.60
Purchase #5	$158.98	13.864%	$181.021	$181.02	$181.00	$181.00
Purchase #6	$137.83	9.143%	$150.4318	$150.43	$150.45	$150.40
Purchase #7	$33.55	10.547%	$37.0885	$37.09	$37.10	$37.10
7 purchase totals =	$1,021.80		$1,135.6765	$1,135.68	$1,135.70	$1,135.60