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	$222.29	3.273%	$229.5656	$229.57	$229.55	$229.60
Purchase #2	$28.30	11.251%	$31.484	$31.48	$31.50	$31.50
Purchase #3	$85.70	11.849%	$95.8546	$95.85	$95.85	$95.90
Purchase #4	$35.96	4.173%	$37.4606	$37.46	$37.45	$37.50
Purchase #5	$206.61	9.319%	$225.864	$225.86	$225.85	$225.90
Purchase #6	$206.27	11.842%	$230.6965	$230.70	$230.70	$230.70
Purchase #7	$127.59	3.263%	$131.7533	$131.75	$131.75	$131.80
7 purchase totals =	$912.72		$982.6786	$982.67	$982.65	$982.90