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	$95.77	9.571%	$104.9361	$104.94	$104.95	$104.90
Purchase #2	$151.57	3.268%	$156.5233	$156.52	$156.50	$156.50
Purchase #3	$41.52	4.513%	$43.3938	$43.39	$43.40	$43.40
Purchase #4	$30.47	4.511%	$31.8445	$31.84	$31.85	$31.80
Purchase #5	$169.95	9.344%	$185.8301	$185.83	$185.85	$185.80
Purchase #6	$174.51	10.789%	$193.3379	$193.34	$193.35	$193.30
Purchase #7	$39.74	6.620%	$42.3708	$42.37	$42.35	$42.40
7 purchase totals =	$703.53		$758.2365	$758.23	$758.25	$758.10