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	$186.35	11.757%	$208.2592	$208.26	$208.25	$208.30
Purchase #2	$217.59	8.607%	$236.318	$236.32	$236.30	$236.30
Purchase #3	$35.80	9.104%	$39.0592	$39.06	$39.05	$39.10
Purchase #4	$147.36	4.190%	$153.5344	$153.53	$153.55	$153.50
Purchase #5	$56.80	3.172%	$58.6017	$58.60	$58.60	$58.60
Purchase #6	$173.54	13.263%	$196.5566	$196.56	$196.55	$196.60
Purchase #7	$123.54	7.743%	$133.1057	$133.11	$133.10	$133.10
7 purchase totals =	$940.98		$1,025.4348	$1,025.44	$1,025.40	$1,025.50