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	$190.82	5.119%	$200.5881	$200.59	$200.60	$200.60
Purchase #2	$83.93	11.251%	$93.373	$93.37	$93.35	$93.40
Purchase #3	$175.35	5.552%	$185.0854	$185.09	$185.10	$185.10
Purchase #4	$145.38	13.762%	$165.3872	$165.39	$165.40	$165.40
Purchase #5	$137.96	4.367%	$143.9847	$143.98	$144.00	$144.00
Purchase #6	$97.61	4.589%	$102.0893	$102.09	$102.10	$102.10
Purchase #7	$153.84	11.749%	$171.9147	$171.91	$171.90	$171.90
7 purchase totals =	$984.89		$1,062.4224	$1,062.42	$1,062.45	$1,062.50