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	$12.82	9.811%	$14.0778	$14.08	$14.10	$14.10
Purchase #2	$20.75	7.331%	$22.2712	$22.27	$22.25	$22.30
Purchase #3	$209.87	3.298%	$216.7915	$216.79	$216.80	$216.80
Purchase #4	$88.99	13.385%	$100.9013	$100.90	$100.90	$100.90
Purchase #5	$56.98	13.774%	$64.8284	$64.83	$64.85	$64.80
Purchase #6	$229.88	3.468%	$237.8522	$237.85	$237.85	$237.90
Purchase #7	$131.51	6.237%	$139.7123	$139.71	$139.70	$139.70
7 purchase totals =	$750.80		$796.4347	$796.43	$796.45	$796.50