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	$158.71	3.159%	$163.7236	$163.72	$163.70	$163.70
Purchase #2	$180.37	11.713%	$201.4967	$201.50	$201.50	$201.50
Purchase #3	$41.86	3.832%	$43.4641	$43.46	$43.45	$43.50
Purchase #4	$31.65	4.628%	$33.1148	$33.11	$33.10	$33.10
Purchase #5	$210.25	13.347%	$238.3121	$238.31	$238.30	$238.30
Purchase #6	$145.81	6.623%	$155.467	$155.47	$155.45	$155.50
Purchase #7	$234.89	11.307%	$261.449	$261.45	$261.45	$261.40
7 purchase totals =	$1,003.54		$1,097.0273	$1,097.02	$1,096.95	$1,097.00