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	$196.68	11.206%	$218.72	$218.72	$218.70	$218.70
Purchase #2	$229.68	6.483%	$244.5702	$244.57	$244.55	$244.60
Purchase #3	$96.78	8.802%	$105.2986	$105.30	$105.30	$105.30
Purchase #4	$50.72	11.421%	$56.5127	$56.51	$56.50	$56.50
Purchase #5	$192.92	12.200%	$216.4562	$216.46	$216.45	$216.50
Purchase #6	$102.60	12.586%	$115.5132	$115.51	$115.50	$115.50
Purchase #7	$48.29	4.542%	$50.4833	$50.48	$50.50	$50.50
7 purchase totals =	$917.67		$1,007.5542	$1,007.55	$1,007.50	$1,007.60