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	$202.65	8.262%	$219.3929	$219.39	$219.40	$219.40
Purchase #2	$16.26	12.529%	$18.2972	$18.30	$18.30	$18.30
Purchase #3	$40.49	4.798%	$42.4327	$42.43	$42.45	$42.40
Purchase #4	$81.93	10.778%	$90.7604	$90.76	$90.75	$90.80
Purchase #5	$188.43	9.359%	$206.0652	$206.07	$206.05	$206.10
Purchase #6	$191.83	8.172%	$207.5063	$207.51	$207.50	$207.50
Purchase #7	$202.78	9.767%	$222.5855	$222.59	$222.60	$222.60
7 purchase totals =	$924.37		$1,007.0402	$1,007.05	$1,007.05	$1,007.10