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	$196.45	7.788%	$211.7495	$211.75	$211.75	$211.70
Purchase #2	$55.98	6.774%	$59.7721	$59.77	$59.75	$59.80
Purchase #3	$174.77	4.414%	$182.4843	$182.48	$182.50	$182.50
Purchase #4	$108.78	13.643%	$123.6209	$123.62	$123.60	$123.60
Purchase #5	$57.27	9.811%	$62.8888	$62.89	$62.90	$62.90
Purchase #6	$113.46	13.634%	$128.9291	$128.93	$128.95	$128.90
Purchase #7	$225.87	6.579%	$240.73	$240.73	$240.75	$240.70
7 purchase totals =	$932.58		$1,010.1747	$1,010.17	$1,010.20	$1,010.10