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	$98.32	7.736%	$105.926	$105.93	$105.95	$105.90
Purchase #2	$242.74	3.497%	$251.2286	$251.23	$251.25	$251.20
Purchase #3	$120.27	5.372%	$126.7309	$126.73	$126.75	$126.70
Purchase #4	$114.54	7.626%	$123.2748	$123.27	$123.25	$123.30
Purchase #5	$108.82	13.390%	$123.391	$123.39	$123.40	$123.40
Purchase #6	$204.60	13.747%	$232.7264	$232.73	$232.75	$232.70
Purchase #7	$196.60	13.548%	$223.2354	$223.24	$223.25	$223.20
7 purchase totals =	$1,085.89		$1,186.5131	$1,186.52	$1,186.60	$1,186.40