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	$184.80	5.797%	$195.5129	$195.51	$195.50	$195.50
Purchase #2	$73.36	4.302%	$76.5159	$76.52	$76.50	$76.50
Purchase #3	$141.40	6.392%	$150.4383	$150.44	$150.45	$150.40
Purchase #4	$119.51	10.717%	$132.3179	$132.32	$132.30	$132.30
Purchase #5	$196.41	10.788%	$217.5987	$217.60	$217.60	$217.60
Purchase #6	$90.53	11.633%	$101.0614	$101.06	$101.05	$101.10
Purchase #7	$248.31	5.867%	$262.8783	$262.88	$262.90	$262.90
7 purchase totals =	$1,054.32		$1,136.3234	$1,136.33	$1,136.30	$1,136.30