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	$54.82	13.745%	$62.355	$62.36	$62.35	$62.40
Purchase #2	$80.54	3.769%	$83.5756	$83.58	$83.60	$83.60
Purchase #3	$152.72	10.628%	$168.9511	$168.95	$168.95	$169.00
Purchase #4	$233.54	7.669%	$251.4502	$251.45	$251.45	$251.50
Purchase #5	$118.63	11.180%	$131.8928	$131.89	$131.90	$131.90
Purchase #6	$196.95	13.354%	$223.2507	$223.25	$223.25	$223.30
Purchase #7	$187.31	13.832%	$213.2187	$213.22	$213.20	$213.20
7 purchase totals =	$1,024.51		$1,134.6941	$1,134.70	$1,134.70	$1,134.90