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	$234.86	10.537%	$259.6072	$259.61	$259.60	$259.60
Purchase #2	$14.64	5.166%	$15.3963	$15.40	$15.40	$15.40
Purchase #3	$145.36	3.387%	$150.2833	$150.28	$150.30	$150.30
Purchase #4	$132.77	4.605%	$138.8841	$138.88	$138.90	$138.90
Purchase #5	$192.92	3.360%	$199.4021	$199.40	$199.40	$199.40
Purchase #6	$92.60	11.282%	$103.0471	$103.05	$103.05	$103.00
Purchase #7	$183.89	7.120%	$196.983	$196.98	$197.00	$197.00
7 purchase totals =	$997.04		$1,063.6031	$1,063.60	$1,063.65	$1,063.60