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	$210.48	5.446%	$221.9427	$221.94	$221.95	$221.90
Purchase #2	$55.27	11.437%	$61.5912	$61.59	$61.60	$61.60
Purchase #3	$140.52	5.509%	$148.2612	$148.26	$148.25	$148.30
Purchase #4	$78.92	8.141%	$85.3449	$85.34	$85.35	$85.30
Purchase #5	$41.86	7.676%	$45.0732	$45.07	$45.05	$45.10
Purchase #6	$137.51	13.424%	$155.9693	$155.97	$155.95	$156.00
Purchase #7	$41.45	6.247%	$44.0394	$44.04	$44.05	$44.00
7 purchase totals =	$706.01		$762.2219	$762.21	$762.20	$762.20