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	$71.54	5.862%	$75.7337	$75.73	$75.75	$75.70
Purchase #2	$67.75	7.115%	$72.5704	$72.57	$72.55	$72.60
Purchase #3	$56.96	4.252%	$59.3819	$59.38	$59.40	$59.40
Purchase #4	$141.70	4.405%	$147.9419	$147.94	$147.95	$147.90
Purchase #5	$224.27	7.476%	$241.0364	$241.04	$241.05	$241.00
Purchase #6	$200.53	13.213%	$227.026	$227.03	$227.05	$227.00
Purchase #7	$212.81	11.184%	$236.6107	$236.61	$236.60	$236.60
7 purchase totals =	$975.56		$1,060.3010	$1,060.30	$1,060.35	$1,060.20