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	$87.54	12.435%	$98.4256	$98.43	$98.45	$98.40
Purchase #2	$75.31	8.726%	$81.8816	$81.88	$81.90	$81.90
Purchase #3	$120.92	5.610%	$127.7036	$127.70	$127.70	$127.70
Purchase #4	$136.62	8.776%	$148.6098	$148.61	$148.60	$148.60
Purchase #5	$166.66	3.441%	$172.3948	$172.39	$172.40	$172.40
Purchase #6	$217.86	3.251%	$224.9426	$224.94	$224.95	$224.90
Purchase #7	$159.83	7.371%	$171.6111	$171.61	$171.60	$171.60
7 purchase totals =	$964.74		$1,025.5691	$1,025.56	$1,025.60	$1,025.50