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	$128.37	10.259%	$141.5395	$141.54	$141.55	$141.50
Purchase #2	$54.64	3.452%	$56.5262	$56.53	$56.55	$56.50
Purchase #3	$208.76	5.350%	$219.9287	$219.93	$219.95	$219.90
Purchase #4	$195.57	7.868%	$210.9574	$210.96	$210.95	$211.00
Purchase #5	$215.62	3.215%	$222.5522	$222.55	$222.55	$222.60
Purchase #6	$105.95	5.769%	$112.0623	$112.06	$112.05	$112.10
Purchase #7	$55.41	7.386%	$59.5026	$59.50	$59.50	$59.50
7 purchase totals =	$964.32		$1,023.0689	$1,023.07	$1,023.10	$1,023.10