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	$91.94	11.738%	$102.7319	$102.73	$102.75	$102.70
Purchase #2	$86.82	10.464%	$95.9048	$95.90	$95.90	$95.90
Purchase #3	$142.42	6.143%	$151.1689	$151.17	$151.15	$151.20
Purchase #4	$139.37	13.496%	$158.1794	$158.18	$158.20	$158.20
Purchase #5	$99.71	12.336%	$112.0102	$112.01	$112.00	$112.00
Purchase #6	$185.30	8.235%	$200.5595	$200.56	$200.55	$200.60
Purchase #7	$186.57	13.846%	$212.4025	$212.40	$212.40	$212.40
7 purchase totals =	$932.13		$1,032.9572	$1,032.95	$1,032.95	$1,033.00