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	$147.36	3.135%	$151.9797	$151.98	$152.00	$152.00
Purchase #2	$40.95	7.637%	$44.0774	$44.08	$44.10	$44.10
Purchase #3	$67.86	6.292%	$72.1298	$72.13	$72.15	$72.10
Purchase #4	$21.58	11.630%	$24.0898	$24.09	$24.10	$24.10
Purchase #5	$198.70	8.675%	$215.9372	$215.94	$215.95	$215.90
Purchase #6	$54.72	8.407%	$59.3203	$59.32	$59.30	$59.30
Purchase #7	$56.25	6.741%	$60.0418	$60.04	$60.05	$60.00
7 purchase totals =	$587.42		$627.5760	$627.58	$627.65	$627.50