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	$200.89	8.435%	$217.8351	$217.84	$217.85	$217.80
Purchase #2	$95.37	8.421%	$103.4011	$103.40	$103.40	$103.40
Purchase #3	$213.35	3.479%	$220.7724	$220.77	$220.75	$220.80
Purchase #4	$99.81	11.653%	$111.4409	$111.44	$111.45	$111.40
Purchase #5	$99.49	9.120%	$108.5635	$108.56	$108.55	$108.60
Purchase #6	$36.60	13.512%	$41.5454	$41.55	$41.55	$41.50
Purchase #7	$219.84	11.394%	$244.8886	$244.89	$244.90	$244.90
7 purchase totals =	$965.35		$1,048.4470	$1,048.45	$1,048.45	$1,048.40