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	$92.25	7.127%	$98.8247	$98.82	$98.80	$98.80
Purchase #2	$205.40	3.567%	$212.7266	$212.73	$212.75	$212.70
Purchase #3	$68.59	6.343%	$72.9407	$72.94	$72.95	$72.90
Purchase #4	$177.34	10.259%	$195.5333	$195.53	$195.55	$195.50
Purchase #5	$58.59	11.533%	$65.3472	$65.35	$65.35	$65.30
Purchase #6	$233.78	9.374%	$255.6945	$255.69	$255.70	$255.70
Purchase #7	$139.93	5.291%	$147.3337	$147.33	$147.35	$147.30
7 purchase totals =	$975.88		$1,048.4007	$1,048.39	$1,048.45	$1,048.20