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	$134.78	12.741%	$151.9523	$151.95	$151.95	$152.00
Purchase #2	$53.30	4.156%	$55.5151	$55.52	$55.50	$55.50
Purchase #3	$38.45	6.664%	$41.0123	$41.01	$41.00	$41.00
Purchase #4	$184.47	6.692%	$196.8147	$196.81	$196.80	$196.80
Purchase #5	$44.71	7.245%	$47.9492	$47.95	$47.95	$47.90
Purchase #6	$187.63	3.494%	$194.1858	$194.19	$194.20	$194.20
Purchase #7	$39.86	11.532%	$44.4567	$44.46	$44.45	$44.50
7 purchase totals =	$683.20		$731.8861	$731.89	$731.85	$731.90