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	$90.52	7.430%	$97.2456	$97.25	$97.25	$97.20
Purchase #2	$70.57	4.739%	$73.9143	$73.91	$73.90	$73.90
Purchase #3	$83.41	5.259%	$87.7965	$87.80	$87.80	$87.80
Purchase #4	$95.91	9.739%	$105.2507	$105.25	$105.25	$105.30
Purchase #5	$235.69	11.484%	$262.7566	$262.76	$262.75	$262.80
Purchase #6	$110.85	11.185%	$123.2486	$123.25	$123.25	$123.20
Purchase #7	$172.37	11.306%	$191.8582	$191.86	$191.85	$191.90
7 purchase totals =	$859.32		$942.0705	$942.08	$942.05	$942.10