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	$41.85	4.697%	$43.8157	$43.82	$43.80	$43.80
Purchase #2	$68.97	4.750%	$72.2461	$72.25	$72.25	$72.20
Purchase #3	$77.56	10.165%	$85.444	$85.44	$85.45	$85.40
Purchase #4	$179.41	11.434%	$199.9237	$199.92	$199.90	$199.90
Purchase #5	$213.53	3.181%	$220.3224	$220.32	$220.30	$220.30
Purchase #6	$53.95	9.748%	$59.209	$59.21	$59.20	$59.20
Purchase #7	$52.30	9.856%	$57.4547	$57.45	$57.45	$57.50
7 purchase totals =	$687.57		$738.4156	$738.41	$738.35	$738.30