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	$59.46	8.570%	$64.5557	$64.56	$64.55	$64.60
Purchase #2	$234.45	8.626%	$254.6737	$254.67	$254.65	$254.70
Purchase #3	$238.58	12.580%	$268.5934	$268.59	$268.60	$268.60
Purchase #4	$241.32	6.242%	$256.3832	$256.38	$256.40	$256.40
Purchase #5	$114.94	11.216%	$127.8317	$127.83	$127.85	$127.80
Purchase #6	$99.97	11.453%	$111.4196	$111.42	$111.40	$111.40
Purchase #7	$96.66	6.595%	$103.0347	$103.03	$103.05	$103.00
7 purchase totals =	$1,085.38		$1,186.4920	$1,186.48	$1,186.50	$1,186.50