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	$58.96	5.817%	$62.3897	$62.39	$62.40	$62.40
Purchase #2	$143.83	4.658%	$150.5296	$150.53	$150.55	$150.50
Purchase #3	$228.99	7.108%	$245.2666	$245.27	$245.25	$245.30
Purchase #4	$33.50	11.629%	$37.3957	$37.40	$37.40	$37.40
Purchase #5	$203.60	10.152%	$224.2695	$224.27	$224.25	$224.30
Purchase #6	$176.43	7.245%	$189.2124	$189.21	$189.20	$189.20
Purchase #7	$136.64	4.443%	$142.7109	$142.71	$142.70	$142.70
7 purchase totals =	$981.95		$1,051.7744	$1,051.78	$1,051.75	$1,051.80