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	$183.84	12.845%	$207.4542	$207.45	$207.45	$207.50
Purchase #2	$49.56	8.728%	$53.8856	$53.89	$53.90	$53.90
Purchase #3	$49.89	11.642%	$55.6982	$55.70	$55.70	$55.70
Purchase #4	$92.51	8.601%	$100.4668	$100.47	$100.45	$100.50
Purchase #5	$215.90	7.661%	$232.4401	$232.44	$232.45	$232.40
Purchase #6	$108.67	4.220%	$113.2559	$113.26	$113.25	$113.30
Purchase #7	$232.62	10.144%	$256.217	$256.22	$256.20	$256.20
7 purchase totals =	$932.99		$1,019.4178	$1,019.43	$1,019.40	$1,019.50