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	$211.72	9.366%	$231.5497	$231.55	$231.55	$231.50
Purchase #2	$31.78	11.372%	$35.394	$35.39	$35.40	$35.40
Purchase #3	$66.45	7.713%	$71.5753	$71.58	$71.60	$71.60
Purchase #4	$188.35	11.468%	$209.95	$209.95	$209.95	$210.00
Purchase #5	$175.55	3.263%	$181.2782	$181.28	$181.30	$181.30
Purchase #6	$87.31	4.867%	$91.5594	$91.56	$91.55	$91.60
Purchase #7	$217.30	6.455%	$231.3267	$231.33	$231.35	$231.30
7 purchase totals =	$978.46		$1,052.6333	$1,052.64	$1,052.70	$1,052.70