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	$132.70	7.722%	$142.9471	$142.95	$142.95	$142.90
Purchase #2	$180.43	3.583%	$186.8948	$186.89	$186.90	$186.90
Purchase #3	$113.48	4.670%	$118.7795	$118.78	$118.80	$118.80
Purchase #4	$99.36	9.241%	$108.5419	$108.54	$108.55	$108.50
Purchase #5	$172.44	11.180%	$191.7188	$191.72	$191.70	$191.70
Purchase #6	$65.37	3.507%	$67.6625	$67.66	$67.65	$67.70
Purchase #7	$193.70	9.418%	$211.9427	$211.94	$211.95	$211.90
7 purchase totals =	$957.48		$1,028.4873	$1,028.48	$1,028.50	$1,028.40