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	$65.26	11.191%	$72.5632	$72.56	$72.55	$72.60
Purchase #2	$55.65	4.392%	$58.0941	$58.09	$58.10	$58.10
Purchase #3	$239.30	7.546%	$257.3576	$257.36	$257.35	$257.40
Purchase #4	$186.72	5.158%	$196.351	$196.35	$196.35	$196.40
Purchase #5	$58.73	6.524%	$62.5615	$62.56	$62.55	$62.60
Purchase #6	$143.36	13.179%	$162.2534	$162.25	$162.25	$162.30
Purchase #7	$171.39	12.293%	$192.459	$192.46	$192.45	$192.50
7 purchase totals =	$920.41		$1,001.6398	$1,001.63	$1,001.60	$1,001.90