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	$203.88	3.606%	$211.2319	$211.23	$211.25	$211.20
Purchase #2	$248.45	5.793%	$262.8427	$262.84	$262.85	$262.80
Purchase #3	$132.32	12.138%	$148.381	$148.38	$148.40	$148.40
Purchase #4	$91.33	13.756%	$103.8934	$103.89	$103.90	$103.90
Purchase #5	$250.68	5.275%	$263.9034	$263.90	$263.90	$263.90
Purchase #6	$7.86	5.429%	$8.2867	$8.29	$8.30	$8.30
Purchase #7	$243.83	5.296%	$256.7432	$256.74	$256.75	$256.70
7 purchase totals =	$1,178.35		$1,255.2823	$1,255.27	$1,255.35	$1,255.20