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	$203.79	3.724%	$211.3791	$211.38	$211.40	$211.40
Purchase #2	$90.83	4.207%	$94.6512	$94.65	$94.65	$94.70
Purchase #3	$179.46	9.248%	$196.0565	$196.06	$196.05	$196.10
Purchase #4	$35.55	12.105%	$39.8533	$39.85	$39.85	$39.90
Purchase #5	$249.28	13.404%	$282.6935	$282.69	$282.70	$282.70
Purchase #6	$36.54	3.591%	$37.8522	$37.85	$37.85	$37.90
Purchase #7	$190.43	5.158%	$200.2524	$200.25	$200.25	$200.30
7 purchase totals =	$985.88		$1,062.7382	$1,062.73	$1,062.75	$1,063.00