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	$125.33	4.710%	$131.233	$131.23	$131.25	$131.20
Purchase #2	$126.63	4.790%	$132.6956	$132.70	$132.70	$132.70
Purchase #3	$136.33	13.737%	$155.0577	$155.06	$155.05	$155.10
Purchase #4	$128.55	3.395%	$132.9143	$132.91	$132.90	$132.90
Purchase #5	$10.33	12.191%	$11.5893	$11.59	$11.60	$11.60
Purchase #6	$99.70	11.385%	$111.0508	$111.05	$111.05	$111.10
Purchase #7	$31.44	7.525%	$33.8059	$33.81	$33.80	$33.80
7 purchase totals =	$658.31		$708.3466	$708.35	$708.35	$708.40