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	$110.98	13.111%	$125.5306	$125.53	$125.55	$125.50
Purchase #2	$69.91	11.663%	$78.0636	$78.06	$78.05	$78.10
Purchase #3	$72.87	4.464%	$76.1229	$76.12	$76.10	$76.10
Purchase #4	$55.82	10.160%	$61.4913	$61.49	$61.50	$61.50
Purchase #5	$86.30	13.390%	$97.8556	$97.86	$97.85	$97.90
Purchase #6	$108.37	13.704%	$123.221	$123.22	$123.20	$123.20
Purchase #7	$156.62	5.494%	$165.2247	$165.22	$165.20	$165.20
7 purchase totals =	$660.87		$727.5097	$727.50	$727.45	$727.50