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	$52.71	4.262%	$54.9565	$54.96	$54.95	$55.00
Purchase #2	$6.71	10.212%	$7.3952	$7.40	$7.40	$7.40
Purchase #3	$29.71	9.755%	$32.6082	$32.61	$32.60	$32.60
Purchase #4	$56.76	10.210%	$62.5552	$62.56	$62.55	$62.60
Purchase #5	$225.83	7.272%	$242.2524	$242.25	$242.25	$242.30
Purchase #6	$67.59	6.569%	$72.03	$72.03	$72.05	$72.00
Purchase #7	$13.69	3.581%	$14.1802	$14.18	$14.20	$14.20
7 purchase totals =	$453.00		$485.9777	$485.99	$486.00	$486.10