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	$57.40	6.167%	$60.9399	$60.94	$60.95	$60.90
Purchase #2	$35.83	10.425%	$39.5653	$39.57	$39.55	$39.60
Purchase #3	$47.55	11.165%	$52.859	$52.86	$52.85	$52.90
Purchase #4	$205.71	13.360%	$233.1929	$233.19	$233.20	$233.20
Purchase #5	$32.91	13.415%	$37.3249	$37.32	$37.30	$37.30
Purchase #6	$92.95	10.854%	$103.0388	$103.04	$103.05	$103.00
Purchase #7	$161.97	6.196%	$172.0057	$172.01	$172.00	$172.00
7 purchase totals =	$634.32		$698.9265	$698.93	$698.90	$698.90