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	$186.54	7.461%	$200.4577	$200.46	$200.45	$200.50
Purchase #2	$136.53	13.520%	$154.9889	$154.99	$155.00	$155.00
Purchase #3	$92.26	12.151%	$103.4705	$103.47	$103.45	$103.50
Purchase #4	$21.65	4.795%	$22.6881	$22.69	$22.70	$22.70
Purchase #5	$136.43	6.467%	$145.2529	$145.25	$145.25	$145.30
Purchase #6	$150.36	12.861%	$169.6978	$169.70	$169.70	$169.70
Purchase #7	$236.83	11.777%	$264.7215	$264.72	$264.70	$264.70
7 purchase totals =	$960.60		$1,061.2774	$1,061.28	$1,061.25	$1,061.40