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	$90.90	4.127%	$94.6514	$94.65	$94.65	$94.70
Purchase #2	$52.47	5.638%	$55.4283	$55.43	$55.45	$55.40
Purchase #3	$181.60	3.735%	$188.3828	$188.38	$188.40	$188.40
Purchase #4	$27.56	12.621%	$31.0383	$31.04	$31.05	$31.00
Purchase #5	$26.81	8.320%	$29.0406	$29.04	$29.05	$29.00
Purchase #6	$221.95	9.807%	$243.7166	$243.72	$243.70	$243.70
Purchase #7	$75.43	10.776%	$83.5583	$83.56	$83.55	$83.60
7 purchase totals =	$676.72		$725.8163	$725.82	$725.85	$725.80