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	$232.66	5.427%	$245.2865	$245.29	$245.30	$245.30
Purchase #2	$151.36	4.786%	$158.6041	$158.60	$158.60	$158.60
Purchase #3	$227.52	6.118%	$241.4397	$241.44	$241.45	$241.40
Purchase #4	$165.83	12.632%	$186.7776	$186.78	$186.80	$186.80
Purchase #5	$54.92	8.512%	$59.5948	$59.59	$59.60	$59.60
Purchase #6	$78.27	9.203%	$85.4732	$85.47	$85.45	$85.50
Purchase #7	$216.49	6.726%	$231.0511	$231.05	$231.05	$231.10
7 purchase totals =	$1,127.05		$1,208.2270	$1,208.22	$1,208.25	$1,208.30