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	$163.38	13.740%	$185.8284	$185.83	$185.85	$185.80
Purchase #2	$59.58	3.817%	$61.8542	$61.85	$61.85	$61.90
Purchase #3	$71.54	13.251%	$81.0198	$81.02	$81.00	$81.00
Purchase #4	$246.58	6.190%	$261.8433	$261.84	$261.85	$261.80
Purchase #5	$162.91	5.475%	$171.8293	$171.83	$171.85	$171.80
Purchase #6	$216.50	6.869%	$231.3714	$231.37	$231.35	$231.40
Purchase #7	$127.88	9.365%	$139.856	$139.86	$139.85	$139.90
7 purchase totals =	$1,048.37		$1,133.6024	$1,133.60	$1,133.60	$1,133.60