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	$103.51	10.242%	$114.1115	$114.11	$114.10	$114.10
Purchase #2	$150.32	3.647%	$155.8022	$155.80	$155.80	$155.80
Purchase #3	$144.66	8.599%	$157.0993	$157.10	$157.10	$157.10
Purchase #4	$12.93	7.152%	$13.8548	$13.85	$13.85	$13.90
Purchase #5	$216.25	10.362%	$238.6578	$238.66	$238.65	$238.70
Purchase #6	$234.31	11.824%	$262.0148	$262.01	$262.00	$262.00
Purchase #7	$83.71	8.450%	$90.7835	$90.78	$90.80	$90.80
7 purchase totals =	$945.69		$1,032.3239	$1,032.31	$1,032.30	$1,032.40