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	$212.92	10.325%	$234.904	$234.90	$234.90	$234.90
Purchase #2	$41.86	13.175%	$47.3751	$47.38	$47.40	$47.40
Purchase #3	$207.82	3.728%	$215.5675	$215.57	$215.55	$215.60
Purchase #4	$200.86	13.710%	$228.3979	$228.40	$228.40	$228.40
Purchase #5	$206.71	5.723%	$218.54	$218.54	$218.55	$218.50
Purchase #6	$7.96	7.345%	$8.5447	$8.54	$8.55	$8.50
Purchase #7	$146.76	3.685%	$152.1681	$152.17	$152.15	$152.20
7 purchase totals =	$1,024.89		$1,105.4973	$1,105.50	$1,105.50	$1,105.50