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	$220.85	9.160%	$241.0799	$241.08	$241.10	$241.10
Purchase #2	$237.60	11.516%	$264.962	$264.96	$264.95	$265.00
Purchase #3	$126.89	8.693%	$137.9205	$137.92	$137.90	$137.90
Purchase #4	$98.88	12.415%	$111.156	$111.16	$111.15	$111.20
Purchase #5	$215.90	13.320%	$244.6579	$244.66	$244.65	$244.70
Purchase #6	$189.89	11.800%	$212.297	$212.30	$212.30	$212.30
Purchase #7	$175.61	12.103%	$196.8641	$196.86	$196.85	$196.90
7 purchase totals =	$1,265.62		$1,408.9374	$1,408.94	$1,408.90	$1,409.10