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	$125.98	4.368%	$131.4828	$131.48	$131.50	$131.50
Purchase #2	$76.46	13.194%	$86.5481	$86.55	$86.55	$86.50
Purchase #3	$48.43	6.125%	$51.3963	$51.40	$51.40	$51.40
Purchase #4	$32.92	5.769%	$34.8192	$34.82	$34.80	$34.80
Purchase #5	$147.57	3.529%	$152.7777	$152.78	$152.80	$152.80
Purchase #6	$62.43	3.211%	$64.4346	$64.43	$64.45	$64.40
Purchase #7	$215.59	6.797%	$230.2437	$230.24	$230.25	$230.20
7 purchase totals =	$709.38		$751.7024	$751.70	$751.75	$751.60