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	$44.42	9.287%	$48.5453	$48.55	$48.55	$48.50
Purchase #2	$135.87	7.163%	$145.6024	$145.60	$145.60	$145.60
Purchase #3	$234.33	11.544%	$261.3811	$261.38	$261.40	$261.40
Purchase #4	$250.60	4.614%	$262.1627	$262.16	$262.15	$262.20
Purchase #5	$115.39	10.572%	$127.589	$127.59	$127.60	$127.60
Purchase #6	$146.78	9.199%	$160.2823	$160.28	$160.30	$160.30
Purchase #7	$174.67	9.526%	$191.3091	$191.31	$191.30	$191.30
7 purchase totals =	$1,102.06		$1,196.8719	$1,196.87	$1,196.90	$1,196.90