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	$96.32	13.723%	$109.538	$109.54	$109.55	$109.50
Purchase #2	$212.52	3.634%	$220.243	$220.24	$220.25	$220.20
Purchase #3	$221.56	13.714%	$251.9447	$251.94	$251.95	$251.90
Purchase #4	$215.47	4.322%	$224.7826	$224.78	$224.80	$224.80
Purchase #5	$43.69	4.304%	$45.5704	$45.57	$45.55	$45.60
Purchase #6	$123.30	9.127%	$134.5536	$134.55	$134.55	$134.60
Purchase #7	$158.66	10.166%	$174.7894	$174.79	$174.80	$174.80
7 purchase totals =	$1,071.52		$1,161.4217	$1,161.41	$1,161.45	$1,161.40