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	$120.71	9.225%	$131.8455	$131.85	$131.85	$131.80
Purchase #2	$94.90	11.804%	$106.102	$106.10	$106.10	$106.10
Purchase #3	$137.81	6.590%	$146.8917	$146.89	$146.90	$146.90
Purchase #4	$231.81	13.555%	$263.2318	$263.23	$263.25	$263.20
Purchase #5	$129.87	12.835%	$146.5388	$146.54	$146.55	$146.50
Purchase #6	$82.59	13.572%	$93.7991	$93.80	$93.80	$93.80
Purchase #7	$162.54	13.565%	$184.5886	$184.59	$184.60	$184.60
7 purchase totals =	$960.23		$1,072.9975	$1,073.00	$1,073.05	$1,072.90