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	$59.35	9.419%	$64.9402	$64.94	$64.95	$64.90
Purchase #2	$64.94	10.323%	$71.6438	$71.64	$71.65	$71.60
Purchase #3	$112.92	5.336%	$118.9454	$118.95	$118.95	$118.90
Purchase #4	$172.94	3.250%	$178.5606	$178.56	$178.55	$178.60
Purchase #5	$166.75	3.172%	$172.0393	$172.04	$172.05	$172.00
Purchase #6	$154.50	8.127%	$167.0562	$167.06	$167.05	$167.10
Purchase #7	$81.97	12.151%	$91.9302	$91.93	$91.95	$91.90
7 purchase totals =	$813.37		$865.1157	$865.12	$865.15	$865.00