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	$116.78	7.141%	$125.1193	$125.12	$125.10	$125.10
Purchase #2	$152.29	10.827%	$168.7784	$168.78	$168.80	$168.80
Purchase #3	$48.29	13.854%	$54.9801	$54.98	$55.00	$55.00
Purchase #4	$217.97	4.651%	$228.1078	$228.11	$228.10	$228.10
Purchase #5	$215.54	3.291%	$222.6334	$222.63	$222.65	$222.60
Purchase #6	$214.77	3.687%	$222.6886	$222.69	$222.70	$222.70
Purchase #7	$66.73	9.638%	$73.1614	$73.16	$73.15	$73.20
7 purchase totals =	$1,032.37		$1,095.4690	$1,095.47	$1,095.50	$1,095.50