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	$12.57	12.217%	$14.1057	$14.11	$14.10	$14.10
Purchase #2	$192.54	10.128%	$212.0405	$212.04	$212.05	$212.00
Purchase #3	$164.38	13.612%	$186.7554	$186.76	$186.75	$186.80
Purchase #4	$147.27	6.193%	$156.3904	$156.39	$156.40	$156.40
Purchase #5	$207.76	10.653%	$229.8927	$229.89	$229.90	$229.90
Purchase #6	$230.63	5.127%	$242.4544	$242.45	$242.45	$242.50
Purchase #7	$93.25	13.480%	$105.8201	$105.82	$105.80	$105.80
7 purchase totals =	$1,048.40		$1,147.4592	$1,147.46	$1,147.45	$1,147.50