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	$88.48	7.397%	$95.0249	$95.02	$95.00	$95.00
Purchase #2	$53.50	7.123%	$57.3108	$57.31	$57.30	$57.30
Purchase #3	$109.63	5.394%	$115.5434	$115.54	$115.55	$115.50
Purchase #4	$241.27	12.837%	$272.2418	$272.24	$272.25	$272.20
Purchase #5	$28.71	12.194%	$32.2109	$32.21	$32.20	$32.20
Purchase #6	$18.62	6.857%	$19.8968	$19.90	$19.90	$19.90
Purchase #7	$127.39	9.582%	$139.5965	$139.60	$139.60	$139.60
7 purchase totals =	$667.60		$731.8251	$731.82	$731.80	$731.70