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	$83.33	3.136%	$85.9432	$85.94	$85.95	$85.90
Purchase #2	$98.97	13.716%	$112.5447	$112.54	$112.55	$112.50
Purchase #3	$99.58	4.754%	$104.314	$104.31	$104.30	$104.30
Purchase #4	$106.71	12.732%	$120.2963	$120.30	$120.30	$120.30
Purchase #5	$54.62	12.776%	$61.5983	$61.60	$61.60	$61.60
Purchase #6	$19.95	13.431%	$22.6295	$22.63	$22.65	$22.60
Purchase #7	$207.64	7.301%	$222.7998	$222.80	$222.80	$222.80
7 purchase totals =	$670.80		$730.1258	$730.12	$730.15	$730.00