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	$208.97	11.526%	$233.0559	$233.06	$233.05	$233.10
Purchase #2	$85.33	3.787%	$88.5614	$88.56	$88.55	$88.60
Purchase #3	$119.94	10.493%	$132.5253	$132.53	$132.55	$132.50
Purchase #4	$36.49	5.256%	$38.4079	$38.41	$38.40	$38.40
Purchase #5	$220.59	12.298%	$247.7182	$247.72	$247.70	$247.70
Purchase #6	$213.43	11.381%	$237.7205	$237.72	$237.70	$237.70
Purchase #7	$55.70	6.220%	$59.1645	$59.16	$59.15	$59.20
7 purchase totals =	$940.45		$1,037.1537	$1,037.16	$1,037.10	$1,037.20