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	$125.67	5.843%	$133.0129	$133.01	$133.00	$133.00
Purchase #2	$208.28	11.443%	$232.1135	$232.11	$232.10	$232.10
Purchase #3	$208.71	12.398%	$234.5859	$234.59	$234.60	$234.60
Purchase #4	$42.44	7.535%	$45.6379	$45.64	$45.65	$45.60
Purchase #5	$121.89	13.336%	$138.1453	$138.15	$138.15	$138.10
Purchase #6	$113.32	12.500%	$127.485	$127.49	$127.50	$127.50
Purchase #7	$137.62	13.762%	$156.5593	$156.56	$156.55	$156.60
7 purchase totals =	$957.93		$1,067.5398	$1,067.55	$1,067.55	$1,067.50