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	$197.92	10.835%	$219.3646	$219.36	$219.35	$219.40
Purchase #2	$204.63	5.382%	$215.6432	$215.64	$215.65	$215.60
Purchase #3	$7.49	11.355%	$8.3405	$8.34	$8.35	$8.30
Purchase #4	$41.33	5.289%	$43.5159	$43.52	$43.50	$43.50
Purchase #5	$167.81	10.609%	$185.613	$185.61	$185.60	$185.60
Purchase #6	$81.52	9.873%	$89.5685	$89.57	$89.55	$89.60
Purchase #7	$9.97	6.577%	$10.6257	$10.63	$10.65	$10.60
7 purchase totals =	$710.67		$772.6714	$772.67	$772.65	$772.60