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	$161.50	6.748%	$172.398	$172.40	$172.40	$172.40
Purchase #2	$5.48	13.649%	$6.228	$6.23	$6.25	$6.20
Purchase #3	$233.57	5.603%	$246.6569	$246.66	$246.65	$246.70
Purchase #4	$96.59	9.186%	$105.4628	$105.46	$105.45	$105.50
Purchase #5	$235.37	8.609%	$255.633	$255.63	$255.65	$255.60
Purchase #6	$176.69	6.673%	$188.4805	$188.48	$188.50	$188.50
Purchase #7	$116.98	7.249%	$125.4599	$125.46	$125.45	$125.50
7 purchase totals =	$1,026.18		$1,100.3191	$1,100.32	$1,100.35	$1,100.40