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	$63.77	12.821%	$71.946	$71.95	$71.95	$71.90
Purchase #2	$192.51	10.669%	$213.0489	$213.05	$213.05	$213.00
Purchase #3	$209.62	11.296%	$233.2987	$233.30	$233.30	$233.30
Purchase #4	$39.34	11.631%	$43.9156	$43.92	$43.90	$43.90
Purchase #5	$214.47	3.234%	$221.406	$221.41	$221.40	$221.40
Purchase #6	$57.38	3.496%	$59.386	$59.39	$59.40	$59.40
Purchase #7	$169.83	12.471%	$191.0095	$191.01	$191.00	$191.00
7 purchase totals =	$946.92		$1,034.0107	$1,034.03	$1,034.00	$1,033.90