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	$193.75	11.289%	$215.6224	$215.62	$215.60	$215.60
Purchase #2	$109.83	7.446%	$118.0079	$118.01	$118.00	$118.00
Purchase #3	$246.38	6.643%	$262.747	$262.75	$262.75	$262.70
Purchase #4	$28.42	11.725%	$31.7522	$31.75	$31.75	$31.80
Purchase #5	$196.28	9.197%	$214.3319	$214.33	$214.35	$214.30
Purchase #6	$211.62	5.664%	$223.6062	$223.61	$223.60	$223.60
Purchase #7	$80.91	11.621%	$90.3126	$90.31	$90.30	$90.30
7 purchase totals =	$1,067.19		$1,156.3802	$1,156.38	$1,156.35	$1,156.30