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	$189.69	3.563%	$196.4487	$196.45	$196.45	$196.40
Purchase #2	$177.48	6.506%	$189.0268	$189.03	$189.05	$189.00
Purchase #3	$83.35	13.810%	$94.8606	$94.86	$94.85	$94.90
Purchase #4	$149.31	12.704%	$168.2783	$168.28	$168.30	$168.30
Purchase #5	$53.76	12.196%	$60.3166	$60.32	$60.30	$60.30
Purchase #6	$105.41	3.328%	$108.918	$108.92	$108.90	$108.90
Purchase #7	$133.44	13.326%	$151.2222	$151.22	$151.20	$151.20
7 purchase totals =	$892.44		$969.0712	$969.08	$969.05	$969.00