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	$148.77	4.384%	$155.2921	$155.29	$155.30	$155.30
Purchase #2	$152.76	4.575%	$159.7488	$159.75	$159.75	$159.70
Purchase #3	$73.58	3.462%	$76.1273	$76.13	$76.15	$76.10
Purchase #4	$180.94	13.678%	$205.689	$205.69	$205.70	$205.70
Purchase #5	$27.40	11.267%	$30.4872	$30.49	$30.50	$30.50
Purchase #6	$250.32	5.654%	$264.4731	$264.47	$264.45	$264.50
Purchase #7	$91.83	9.364%	$100.429	$100.43	$100.45	$100.40
7 purchase totals =	$925.60		$992.2465	$992.25	$992.30	$992.20