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	$119.72	5.115%	$125.8437	$125.84	$125.85	$125.80
Purchase #2	$95.73	10.657%	$105.9319	$105.93	$105.95	$105.90
Purchase #3	$71.58	13.315%	$81.1109	$81.11	$81.10	$81.10
Purchase #4	$190.90	13.753%	$217.1545	$217.15	$217.15	$217.20
Purchase #5	$118.43	11.400%	$131.931	$131.93	$131.95	$131.90
Purchase #6	$238.98	12.619%	$269.1369	$269.14	$269.15	$269.10
Purchase #7	$79.54	9.411%	$87.0255	$87.03	$87.05	$87.00
7 purchase totals =	$914.88		$1,018.1344	$1,018.13	$1,018.20	$1,018.00