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	$105.31	7.250%	$112.945	$112.95	$112.95	$112.90
Purchase #2	$43.87	4.319%	$45.7647	$45.76	$45.75	$45.80
Purchase #3	$124.29	7.692%	$133.8504	$133.85	$133.85	$133.90
Purchase #4	$165.61	10.470%	$182.9494	$182.95	$182.95	$182.90
Purchase #5	$78.53	9.373%	$85.8906	$85.89	$85.90	$85.90
Purchase #6	$62.65	3.340%	$64.7425	$64.74	$64.75	$64.70
Purchase #7	$247.82	9.622%	$271.6652	$271.67	$271.65	$271.70
7 purchase totals =	$828.08		$897.8078	$897.81	$897.80	$897.80