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	$13.58	5.468%	$14.3226	$14.32	$14.30	$14.30
Purchase #2	$29.42	13.851%	$33.495	$33.50	$33.50	$33.50
Purchase #3	$72.41	10.287%	$79.8588	$79.86	$79.85	$79.90
Purchase #4	$42.25	8.826%	$45.979	$45.98	$46.00	$46.00
Purchase #5	$68.71	4.639%	$71.8975	$71.90	$71.90	$71.90
Purchase #6	$183.27	5.800%	$193.8997	$193.90	$193.90	$193.90
Purchase #7	$42.44	7.268%	$45.5245	$45.52	$45.50	$45.50
7 purchase totals =	$452.08		$484.9771	$484.98	$484.95	$485.00