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	$168.27	7.213%	$180.4073	$180.41	$180.40	$180.40
Purchase #2	$181.91	3.187%	$187.7075	$187.71	$187.70	$187.70
Purchase #3	$119.95	10.818%	$132.9262	$132.93	$132.95	$132.90
Purchase #4	$112.32	13.612%	$127.609	$127.61	$127.60	$127.60
Purchase #5	$67.47	13.368%	$76.4894	$76.49	$76.50	$76.50
Purchase #6	$147.57	7.314%	$158.3633	$158.36	$158.35	$158.40
Purchase #7	$238.34	4.846%	$249.89	$249.89	$249.90	$249.90
7 purchase totals =	$1,035.83		$1,113.3927	$1,113.40	$1,113.40	$1,113.40