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	$21.94	12.846%	$24.7584	$24.76	$24.75	$24.80
Purchase #2	$104.68	13.203%	$118.5009	$118.50	$118.50	$118.50
Purchase #3	$182.71	4.627%	$191.164	$191.16	$191.15	$191.20
Purchase #4	$108.93	10.454%	$120.3175	$120.32	$120.30	$120.30
Purchase #5	$221.49	4.815%	$232.1547	$232.15	$232.15	$232.20
Purchase #6	$173.63	6.826%	$185.482	$185.48	$185.50	$185.50
Purchase #7	$166.33	3.763%	$172.589	$172.59	$172.60	$172.60
7 purchase totals =	$979.71		$1,044.9665	$1,044.96	$1,044.95	$1,045.10