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	$166.49	10.800%	$184.4709	$184.47	$184.45	$184.50
Purchase #2	$99.91	10.835%	$110.7352	$110.74	$110.75	$110.70
Purchase #3	$227.89	6.163%	$241.9349	$241.93	$241.95	$241.90
Purchase #4	$164.64	5.360%	$173.4647	$173.46	$173.45	$173.50
Purchase #5	$110.43	4.105%	$114.9632	$114.96	$114.95	$115.00
Purchase #6	$117.40	9.798%	$128.9029	$128.90	$128.90	$128.90
Purchase #7	$55.54	12.789%	$62.643	$62.64	$62.65	$62.60
7 purchase totals =	$942.30		$1,017.1148	$1,017.10	$1,017.10	$1,017.10