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	$43.33	7.108%	$46.4099	$46.41	$46.40	$46.40
Purchase #2	$108.39	13.624%	$123.1571	$123.16	$123.15	$123.20
Purchase #3	$57.34	7.411%	$61.5895	$61.59	$61.60	$61.60
Purchase #4	$241.40	5.136%	$253.7983	$253.80	$253.80	$253.80
Purchase #5	$221.55	7.549%	$238.2748	$238.27	$238.25	$238.30
Purchase #6	$24.40	8.331%	$26.4328	$26.43	$26.45	$26.40
Purchase #7	$7.28	4.505%	$7.608	$7.61	$7.60	$7.60
7 purchase totals =	$703.69		$757.2704	$757.27	$757.25	$757.30