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	$126.49	13.609%	$143.704	$143.70	$143.70	$143.70
Purchase #2	$113.99	8.734%	$123.9459	$123.95	$123.95	$123.90
Purchase #3	$5.61	13.109%	$6.3454	$6.35	$6.35	$6.30
Purchase #4	$42.64	11.476%	$47.5334	$47.53	$47.55	$47.50
Purchase #5	$197.28	7.292%	$211.6657	$211.67	$211.65	$211.70
Purchase #6	$54.47	12.792%	$61.4378	$61.44	$61.45	$61.40
Purchase #7	$164.83	4.592%	$172.399	$172.40	$172.40	$172.40
7 purchase totals =	$705.31		$767.0312	$767.04	$767.05	$766.90