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	$44.65	11.534%	$49.7999	$49.80	$49.80	$49.80
Purchase #2	$215.89	4.450%	$225.4971	$225.50	$225.50	$225.50
Purchase #3	$52.73	6.661%	$56.2423	$56.24	$56.25	$56.20
Purchase #4	$131.36	3.384%	$135.8052	$135.81	$135.80	$135.80
Purchase #5	$190.63	3.291%	$196.9036	$196.90	$196.90	$196.90
Purchase #6	$115.86	9.194%	$126.5122	$126.51	$126.50	$126.50
Purchase #7	$163.50	5.526%	$172.535	$172.54	$172.55	$172.50
7 purchase totals =	$914.62		$963.2953	$963.30	$963.30	$963.20