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	$209.49	12.604%	$235.8941	$235.89	$235.90	$235.90
Purchase #2	$132.59	10.558%	$146.5889	$146.59	$146.60	$146.60
Purchase #3	$27.82	6.804%	$29.7129	$29.71	$29.70	$29.70
Purchase #4	$66.60	11.194%	$74.0552	$74.06	$74.05	$74.10
Purchase #5	$125.30	13.358%	$142.0376	$142.04	$142.05	$142.00
Purchase #6	$144.96	5.420%	$152.8168	$152.82	$152.80	$152.80
Purchase #7	$219.25	11.359%	$244.1546	$244.15	$244.15	$244.20
7 purchase totals =	$926.01		$1,025.2601	$1,025.26	$1,025.25	$1,025.30