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	$146.70	4.160%	$152.8027	$152.80	$152.80	$152.80
Purchase #2	$83.72	13.747%	$95.229	$95.23	$95.25	$95.20
Purchase #3	$144.49	10.365%	$159.4664	$159.47	$159.45	$159.50
Purchase #4	$168.78	4.441%	$176.2755	$176.28	$176.30	$176.30
Purchase #5	$91.69	11.435%	$102.1748	$102.17	$102.15	$102.20
Purchase #6	$216.31	13.639%	$245.8125	$245.81	$245.80	$245.80
Purchase #7	$112.94	5.214%	$118.8287	$118.83	$118.85	$118.80
7 purchase totals =	$964.63		$1,050.5896	$1,050.59	$1,050.60	$1,050.60