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	$62.78	7.736%	$67.6367	$67.64	$67.65	$67.60
Purchase #2	$79.66	13.417%	$90.348	$90.35	$90.35	$90.30
Purchase #3	$159.52	10.504%	$176.276	$176.28	$176.30	$176.30
Purchase #4	$212.35	9.493%	$232.5084	$232.51	$232.50	$232.50
Purchase #5	$78.33	8.546%	$85.0241	$85.02	$85.00	$85.00
Purchase #6	$85.28	10.380%	$94.1321	$94.13	$94.15	$94.10
Purchase #7	$187.46	4.354%	$195.622	$195.62	$195.60	$195.60
7 purchase totals =	$865.38		$941.5473	$941.55	$941.55	$941.40