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	$241.34	7.467%	$259.3609	$259.36	$259.35	$259.40
Purchase #2	$41.84	10.186%	$46.1018	$46.10	$46.10	$46.10
Purchase #3	$66.72	6.704%	$71.1929	$71.19	$71.20	$71.20
Purchase #4	$226.92	10.226%	$250.1248	$250.12	$250.10	$250.10
Purchase #5	$37.60	11.651%	$41.9808	$41.98	$42.00	$42.00
Purchase #6	$144.28	5.643%	$152.4217	$152.42	$152.40	$152.40
Purchase #7	$201.71	3.836%	$209.4476	$209.45	$209.45	$209.40
7 purchase totals =	$960.41		$1,030.6305	$1,030.62	$1,030.60	$1,030.60