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	$196.85	9.627%	$215.8007	$215.80	$215.80	$215.80
Purchase #2	$69.52	13.431%	$78.8572	$78.86	$78.85	$78.90
Purchase #3	$167.63	12.232%	$188.1345	$188.13	$188.15	$188.10
Purchase #4	$85.31	11.386%	$95.0234	$95.02	$95.00	$95.00
Purchase #5	$16.57	12.198%	$18.5912	$18.59	$18.60	$18.60
Purchase #6	$218.88	11.629%	$244.3336	$244.33	$244.35	$244.30
Purchase #7	$242.38	7.804%	$261.2953	$261.30	$261.30	$261.30
7 purchase totals =	$997.14		$1,102.0359	$1,102.03	$1,102.05	$1,102.00