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	$132.26	7.233%	$141.8264	$141.83	$141.85	$141.80
Purchase #2	$137.74	7.365%	$147.8846	$147.88	$147.90	$147.90
Purchase #3	$165.50	5.760%	$175.0328	$175.03	$175.05	$175.00
Purchase #4	$199.30	8.253%	$215.7482	$215.75	$215.75	$215.70
Purchase #5	$29.60	4.778%	$31.0143	$31.01	$31.00	$31.00
Purchase #6	$198.46	5.395%	$209.1669	$209.17	$209.15	$209.20
Purchase #7	$119.69	6.218%	$127.1323	$127.13	$127.15	$127.10
7 purchase totals =	$982.55		$1,047.8055	$1,047.80	$1,047.85	$1,047.70