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	$58.36	7.142%	$62.5281	$62.53	$62.55	$62.50
Purchase #2	$12.71	4.817%	$13.3222	$13.32	$13.30	$13.30
Purchase #3	$215.33	3.709%	$223.3166	$223.32	$223.30	$223.30
Purchase #4	$137.89	8.856%	$150.1015	$150.10	$150.10	$150.10
Purchase #5	$149.71	7.392%	$160.7766	$160.78	$160.80	$160.80
Purchase #6	$118.47	6.643%	$126.34	$126.34	$126.35	$126.30
Purchase #7	$11.25	10.149%	$12.3918	$12.39	$12.40	$12.40
7 purchase totals =	$703.72		$748.7768	$748.78	$748.80	$748.70