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	$196.59	9.435%	$215.1383	$215.14	$215.15	$215.10
Purchase #2	$88.54	4.726%	$92.7244	$92.72	$92.70	$92.70
Purchase #3	$193.59	13.555%	$219.8311	$219.83	$219.85	$219.80
Purchase #4	$24.94	8.173%	$26.9783	$26.98	$27.00	$27.00
Purchase #5	$91.39	8.642%	$99.2879	$99.29	$99.30	$99.30
Purchase #6	$120.80	12.476%	$135.871	$135.87	$135.85	$135.90
Purchase #7	$212.77	6.578%	$226.766	$226.77	$226.75	$226.80
7 purchase totals =	$928.62		$1,016.5970	$1,016.60	$1,016.60	$1,016.60