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	$143.65	5.820%	$152.0104	$152.01	$152.00	$152.00
Purchase #2	$67.26	7.632%	$72.3933	$72.39	$72.40	$72.40
Purchase #3	$214.73	4.788%	$225.0113	$225.01	$225.00	$225.00
Purchase #4	$15.70	3.336%	$16.2238	$16.22	$16.20	$16.20
Purchase #5	$189.34	13.207%	$214.3461	$214.35	$214.35	$214.30
Purchase #6	$155.33	3.387%	$160.591	$160.59	$160.60	$160.60
Purchase #7	$207.58	6.483%	$221.0374	$221.04	$221.05	$221.00
7 purchase totals =	$993.59		$1,061.6133	$1,061.61	$1,061.60	$1,061.50