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	$194.95	10.269%	$214.9694	$214.97	$214.95	$215.00
Purchase #2	$20.87	9.141%	$22.7777	$22.78	$22.80	$22.80
Purchase #3	$143.54	3.335%	$148.3271	$148.33	$148.35	$148.30
Purchase #4	$97.86	9.139%	$106.8034	$106.80	$106.80	$106.80
Purchase #5	$187.49	4.702%	$196.3058	$196.31	$196.30	$196.30
Purchase #6	$166.36	4.214%	$173.3704	$173.37	$173.35	$173.40
Purchase #7	$131.45	4.223%	$137.0011	$137.00	$137.00	$137.00
7 purchase totals =	$942.52		$999.5549	$999.56	$999.55	$999.60