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	$118.25	4.758%	$123.8763	$123.88	$123.90	$123.90
Purchase #2	$124.82	8.721%	$135.7056	$135.71	$135.70	$135.70
Purchase #3	$68.25	5.427%	$71.9539	$71.95	$71.95	$72.00
Purchase #4	$141.62	11.696%	$158.1839	$158.18	$158.20	$158.20
Purchase #5	$199.58	9.623%	$218.7856	$218.79	$218.80	$218.80
Purchase #6	$41.28	13.517%	$46.8598	$46.86	$46.85	$46.90
Purchase #7	$217.76	13.644%	$247.4712	$247.47	$247.45	$247.50
7 purchase totals =	$911.56		$1,002.8363	$1,002.84	$1,002.85	$1,003.00