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	$116.95	7.570%	$125.8031	$125.80	$125.80	$125.80
Purchase #2	$128.29	6.313%	$136.3889	$136.39	$136.40	$136.40
Purchase #3	$149.78	10.111%	$164.9243	$164.92	$164.90	$164.90
Purchase #4	$210.82	9.236%	$230.2913	$230.29	$230.30	$230.30
Purchase #5	$66.88	8.463%	$72.5401	$72.54	$72.55	$72.50
Purchase #6	$115.75	6.269%	$123.0064	$123.01	$123.00	$123.00
Purchase #7	$225.83	8.794%	$245.6895	$245.69	$245.70	$245.70
7 purchase totals =	$1,014.30		$1,098.6436	$1,098.64	$1,098.65	$1,098.60