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	$233.33	3.319%	$241.0742	$241.07	$241.05	$241.10
Purchase #2	$61.29	13.542%	$69.5899	$69.59	$69.60	$69.60
Purchase #3	$56.67	4.272%	$59.0909	$59.09	$59.10	$59.10
Purchase #4	$231.66	5.634%	$244.7117	$244.71	$244.70	$244.70
Purchase #5	$108.88	8.412%	$118.039	$118.04	$118.05	$118.00
Purchase #6	$135.67	4.207%	$141.3776	$141.38	$141.40	$141.40
Purchase #7	$224.87	5.789%	$237.8877	$237.89	$237.90	$237.90
7 purchase totals =	$1,052.37		$1,111.7710	$1,111.77	$1,111.80	$1,111.80