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	$195.76	9.437%	$214.2339	$214.23	$214.25	$214.20
Purchase #2	$192.31	12.361%	$216.0814	$216.08	$216.10	$216.10
Purchase #3	$179.44	9.742%	$196.921	$196.92	$196.90	$196.90
Purchase #4	$78.46	3.794%	$81.4368	$81.44	$81.45	$81.40
Purchase #5	$138.25	4.561%	$144.5556	$144.56	$144.55	$144.60
Purchase #6	$70.67	8.471%	$76.6565	$76.66	$76.65	$76.70
Purchase #7	$87.55	13.639%	$99.4909	$99.49	$99.50	$99.50
7 purchase totals =	$942.44		$1,029.3761	$1,029.38	$1,029.40	$1,029.40