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	$152.61	8.261%	$165.2171	$165.22	$165.20	$165.20
Purchase #2	$76.76	6.298%	$81.5943	$81.59	$81.60	$81.60
Purchase #3	$160.64	4.448%	$167.7853	$167.79	$167.80	$167.80
Purchase #4	$214.57	5.199%	$225.7255	$225.73	$225.75	$225.70
Purchase #5	$158.78	8.326%	$172	$172.00	$172.00	$172.00
Purchase #6	$109.94	8.136%	$118.8847	$118.88	$118.90	$118.90
Purchase #7	$103.45	8.300%	$112.0364	$112.04	$112.05	$112.00
7 purchase totals =	$976.75		$1,043.2433	$1,043.25	$1,043.30	$1,043.20