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	$35.86	5.179%	$37.7172	$37.72	$37.70	$37.70
Purchase #2	$9.50	5.811%	$10.052	$10.05	$10.05	$10.10
Purchase #3	$63.92	12.571%	$71.9554	$71.96	$71.95	$72.00
Purchase #4	$48.49	12.302%	$54.4552	$54.46	$54.45	$54.50
Purchase #5	$91.88	9.253%	$100.3817	$100.38	$100.40	$100.40
Purchase #6	$30.37	13.779%	$34.5547	$34.55	$34.55	$34.60
Purchase #7	$142.80	9.718%	$156.6773	$156.68	$156.70	$156.70
7 purchase totals =	$422.82		$465.7935	$465.80	$465.80	$466.00