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	$176.71	8.225%	$191.2444	$191.24	$191.25	$191.20
Purchase #2	$135.31	13.448%	$153.5065	$153.51	$153.50	$153.50
Purchase #3	$135.65	3.144%	$139.9148	$139.91	$139.90	$139.90
Purchase #4	$146.85	12.115%	$164.6409	$164.64	$164.65	$164.60
Purchase #5	$40.72	10.451%	$44.9756	$44.98	$45.00	$45.00
Purchase #6	$238.97	7.144%	$256.042	$256.04	$256.05	$256.00
Purchase #7	$50.51	13.208%	$57.1814	$57.18	$57.20	$57.20
7 purchase totals =	$924.72		$1,007.5056	$1,007.50	$1,007.55	$1,007.40