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	$196.69	13.279%	$222.8085	$222.81	$222.80	$222.80
Purchase #2	$177.42	3.714%	$184.0094	$184.01	$184.00	$184.00
Purchase #3	$98.36	3.820%	$102.1174	$102.12	$102.10	$102.10
Purchase #4	$72.25	8.179%	$78.1593	$78.16	$78.15	$78.20
Purchase #5	$143.58	10.203%	$158.2295	$158.23	$158.25	$158.20
Purchase #6	$213.34	10.553%	$235.8538	$235.85	$235.85	$235.90
Purchase #7	$40.86	13.254%	$46.2756	$46.28	$46.30	$46.30
7 purchase totals =	$942.50		$1,027.4535	$1,027.46	$1,027.45	$1,027.50