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	$85.78	7.240%	$91.9905	$91.99	$92.00	$92.00
Purchase #2	$188.57	11.168%	$209.6295	$209.63	$209.65	$209.60
Purchase #3	$142.32	6.836%	$152.049	$152.05	$152.05	$152.00
Purchase #4	$5.30	13.164%	$5.9977	$6.00	$6.00	$6.00
Purchase #5	$153.86	9.445%	$168.3921	$168.39	$168.40	$168.40
Purchase #6	$210.68	5.158%	$221.5469	$221.55	$221.55	$221.50
Purchase #7	$148.45	5.484%	$156.591	$156.59	$156.60	$156.60
7 purchase totals =	$934.96		$1,006.1967	$1,006.20	$1,006.25	$1,006.10