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	$48.31	8.449%	$52.3917	$52.39	$52.40	$52.40
Purchase #2	$174.30	6.196%	$185.0996	$185.10	$185.10	$185.10
Purchase #3	$200.69	13.489%	$227.7611	$227.76	$227.75	$227.80
Purchase #4	$224.31	12.870%	$253.1787	$253.18	$253.20	$253.20
Purchase #5	$49.36	9.401%	$54.0003	$54.00	$54.00	$54.00
Purchase #6	$86.77	8.860%	$94.4578	$94.46	$94.45	$94.50
Purchase #7	$208.60	4.394%	$217.7659	$217.77	$217.75	$217.80
7 purchase totals =	$992.34		$1,084.6551	$1,084.66	$1,084.65	$1,084.80