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	$215.82	4.684%	$225.929	$225.93	$225.95	$225.90
Purchase #2	$200.98	4.303%	$209.6282	$209.63	$209.65	$209.60
Purchase #3	$82.99	7.315%	$89.0607	$89.06	$89.05	$89.10
Purchase #4	$142.62	4.345%	$148.8168	$148.82	$148.80	$148.80
Purchase #5	$247.49	6.518%	$263.6214	$263.62	$263.60	$263.60
Purchase #6	$156.81	7.652%	$168.8091	$168.81	$168.80	$168.80
Purchase #7	$5.35	3.384%	$5.531	$5.53	$5.55	$5.50
7 purchase totals =	$1,052.06		$1,111.3962	$1,111.40	$1,111.40	$1,111.30