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	$141.95	7.470%	$152.5537	$152.55	$152.55	$152.60
Purchase #2	$90.74	10.306%	$100.0917	$100.09	$100.10	$100.10
Purchase #3	$132.34	7.744%	$142.5884	$142.59	$142.60	$142.60
Purchase #4	$186.61	10.636%	$206.4578	$206.46	$206.45	$206.50
Purchase #5	$71.70	6.391%	$76.2823	$76.28	$76.30	$76.30
Purchase #6	$16.43	3.510%	$17.0067	$17.01	$17.00	$17.00
Purchase #7	$36.63	9.401%	$40.0736	$40.07	$40.05	$40.10
7 purchase totals =	$676.40		$735.0542	$735.05	$735.05	$735.20