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	$148.50	8.375%	$160.9369	$160.94	$160.95	$160.90
Purchase #2	$221.96	4.377%	$231.6752	$231.68	$231.70	$231.70
Purchase #3	$135.39	4.669%	$141.7114	$141.71	$141.70	$141.70
Purchase #4	$228.50	4.103%	$237.8754	$237.88	$237.90	$237.90
Purchase #5	$114.25	11.277%	$127.134	$127.13	$127.15	$127.10
Purchase #6	$137.66	10.690%	$152.3759	$152.38	$152.40	$152.40
Purchase #7	$98.87	6.620%	$105.4152	$105.42	$105.40	$105.40
7 purchase totals =	$1,085.13		$1,157.1240	$1,157.14	$1,157.20	$1,157.10