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	$225.63	7.116%	$241.6858	$241.69	$241.70	$241.70
Purchase #2	$9.36	13.221%	$10.5975	$10.60	$10.60	$10.60
Purchase #3	$70.85	10.366%	$78.1943	$78.19	$78.20	$78.20
Purchase #4	$194.34	7.568%	$209.0477	$209.05	$209.05	$209.00
Purchase #5	$95.81	10.384%	$105.7589	$105.76	$105.75	$105.80
Purchase #6	$169.75	6.556%	$180.8788	$180.88	$180.90	$180.90
Purchase #7	$248.78	7.383%	$267.1474	$267.15	$267.15	$267.10
7 purchase totals =	$1,014.52		$1,093.3104	$1,093.32	$1,093.35	$1,093.30