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	$118.84	7.240%	$127.444	$127.44	$127.45	$127.40
Purchase #2	$201.38	8.550%	$218.598	$218.60	$218.60	$218.60
Purchase #3	$120.74	7.700%	$130.037	$130.04	$130.05	$130.00
Purchase #4	$180.36	11.358%	$200.8453	$200.85	$200.85	$200.80
Purchase #5	$127.48	3.120%	$131.4574	$131.46	$131.45	$131.50
Purchase #6	$12.80	13.233%	$14.4938	$14.49	$14.50	$14.50
Purchase #7	$110.34	4.603%	$115.419	$115.42	$115.40	$115.40
7 purchase totals =	$871.94		$938.2945	$938.30	$938.30	$938.20