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	$190.26	3.507%	$196.9324	$196.93	$196.95	$196.90
Purchase #2	$101.64	5.127%	$106.8511	$106.85	$106.85	$106.90
Purchase #3	$193.28	11.565%	$215.6328	$215.63	$215.65	$215.60
Purchase #4	$26.25	9.420%	$28.7228	$28.72	$28.70	$28.70
Purchase #5	$246.37	4.262%	$256.8703	$256.87	$256.85	$256.90
Purchase #6	$234.96	4.221%	$244.8777	$244.88	$244.90	$244.90
Purchase #7	$18.32	9.312%	$20.026	$20.03	$20.05	$20.00
7 purchase totals =	$1,011.08		$1,069.9131	$1,069.91	$1,069.95	$1,069.90