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	$162.56	6.864%	$173.7181	$173.72	$173.70	$173.70
Purchase #2	$99.27	5.350%	$104.5809	$104.58	$104.60	$104.60
Purchase #3	$92.86	5.118%	$97.6126	$97.61	$97.60	$97.60
Purchase #4	$212.50	12.190%	$238.4038	$238.40	$238.40	$238.40
Purchase #5	$170.50	9.869%	$187.3266	$187.33	$187.35	$187.30
Purchase #6	$137.51	10.478%	$151.9183	$151.92	$151.90	$151.90
Purchase #7	$63.77	11.115%	$70.858	$70.86	$70.85	$70.90
7 purchase totals =	$938.97		$1,024.4183	$1,024.42	$1,024.40	$1,024.40