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	$200.27	5.684%	$211.6533	$211.65	$211.65	$211.70
Purchase #2	$31.49	4.103%	$32.782	$32.78	$32.80	$32.80
Purchase #3	$54.52	3.367%	$56.3557	$56.36	$56.35	$56.40
Purchase #4	$244.67	8.254%	$264.8651	$264.87	$264.85	$264.90
Purchase #5	$54.92	7.693%	$59.145	$59.15	$59.15	$59.10
Purchase #6	$139.59	6.691%	$148.93	$148.93	$148.95	$148.90
Purchase #7	$135.58	13.187%	$153.4589	$153.46	$153.45	$153.50
7 purchase totals =	$861.04		$927.1900	$927.20	$927.20	$927.30