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	$153.25	3.512%	$158.6321	$158.63	$158.65	$158.60
Purchase #2	$180.78	4.429%	$188.7867	$188.79	$188.80	$188.80
Purchase #3	$129.67	10.174%	$142.8626	$142.86	$142.85	$142.90
Purchase #4	$202.52	6.733%	$216.1557	$216.16	$216.15	$216.20
Purchase #5	$137.62	9.736%	$151.0187	$151.02	$151.00	$151.00
Purchase #6	$169.53	11.198%	$188.514	$188.51	$188.50	$188.50
Purchase #7	$200.85	7.377%	$215.6667	$215.67	$215.65	$215.70
7 purchase totals =	$1,174.22		$1,261.6365	$1,261.64	$1,261.60	$1,261.70