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	$216.56	4.786%	$226.9246	$226.92	$226.90	$226.90
Purchase #2	$149.83	7.182%	$160.5908	$160.59	$160.60	$160.60
Purchase #3	$196.95	9.629%	$215.9143	$215.91	$215.90	$215.90
Purchase #4	$204.74	9.856%	$224.9192	$224.92	$224.90	$224.90
Purchase #5	$217.44	7.248%	$233.2001	$233.20	$233.20	$233.20
Purchase #6	$9.66	8.525%	$10.4835	$10.48	$10.50	$10.50
Purchase #7	$81.28	9.861%	$89.295	$89.30	$89.30	$89.30
7 purchase totals =	$1,076.46		$1,161.3275	$1,161.32	$1,161.30	$1,161.30