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	$217.64	7.215%	$233.3427	$233.34	$233.35	$233.30
Purchase #2	$64.31	4.286%	$67.0663	$67.07	$67.05	$67.10
Purchase #3	$5.78	9.444%	$6.3259	$6.33	$6.35	$6.30
Purchase #4	$153.48	9.798%	$168.518	$168.52	$168.50	$168.50
Purchase #5	$30.34	13.844%	$34.5403	$34.54	$34.55	$34.50
Purchase #6	$117.59	4.622%	$123.025	$123.03	$123.05	$123.00
Purchase #7	$52.47	3.851%	$54.4906	$54.49	$54.50	$54.50
7 purchase totals =	$641.61		$687.3088	$687.32	$687.35	$687.20