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	$13.69	3.162%	$14.1229	$14.12	$14.10	$14.10
Purchase #2	$212.40	12.412%	$238.7631	$238.76	$238.75	$238.80
Purchase #3	$132.77	13.133%	$150.2067	$150.21	$150.20	$150.20
Purchase #4	$225.40	13.775%	$256.4489	$256.45	$256.45	$256.40
Purchase #5	$89.49	5.580%	$94.4835	$94.48	$94.50	$94.50
Purchase #6	$116.31	6.516%	$123.8888	$123.89	$123.90	$123.90
Purchase #7	$151.83	4.799%	$159.1163	$159.12	$159.10	$159.10
7 purchase totals =	$941.89		$1,037.0302	$1,037.03	$1,037.00	$1,037.00