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	$176.61	10.636%	$195.3942	$195.39	$195.40	$195.40
Purchase #2	$65.80	9.456%	$72.022	$72.02	$72.00	$72.00
Purchase #3	$187.97	12.738%	$211.9136	$211.91	$211.90	$211.90
Purchase #4	$231.38	4.737%	$242.3405	$242.34	$242.35	$242.30
Purchase #5	$114.99	11.711%	$128.4565	$128.46	$128.45	$128.50
Purchase #6	$189.57	3.580%	$196.3566	$196.36	$196.35	$196.40
Purchase #7	$172.31	4.493%	$180.0519	$180.05	$180.05	$180.10
7 purchase totals =	$1,138.63		$1,226.5353	$1,226.53	$1,226.50	$1,226.60