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	$144.64	12.247%	$162.3541	$162.35	$162.35	$162.40
Purchase #2	$17.42	12.721%	$19.636	$19.64	$19.65	$19.60
Purchase #3	$33.31	13.732%	$37.8841	$37.88	$37.90	$37.90
Purchase #4	$23.94	4.605%	$25.0424	$25.04	$25.05	$25.00
Purchase #5	$17.78	4.192%	$18.5253	$18.53	$18.55	$18.50
Purchase #6	$22.98	7.329%	$24.6642	$24.66	$24.65	$24.70
Purchase #7	$74.69	11.689%	$83.4205	$83.42	$83.40	$83.40
7 purchase totals =	$334.76		$371.5266	$371.52	$371.55	$371.50