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	$165.31	13.684%	$187.931	$187.93	$187.95	$187.90
Purchase #2	$52.53	13.600%	$59.6741	$59.67	$59.65	$59.70
Purchase #3	$70.41	8.861%	$76.649	$76.65	$76.65	$76.60
Purchase #4	$121.44	9.843%	$133.3933	$133.39	$133.40	$133.40
Purchase #5	$160.86	6.328%	$171.0392	$171.04	$171.05	$171.00
Purchase #6	$174.72	3.730%	$181.2371	$181.24	$181.25	$181.20
Purchase #7	$114.89	7.469%	$123.4711	$123.47	$123.45	$123.50
7 purchase totals =	$860.16		$933.3948	$933.39	$933.40	$933.30