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	$184.61	6.467%	$196.5487	$196.55	$196.55	$196.50
Purchase #2	$46.92	11.874%	$52.4913	$52.49	$52.50	$52.50
Purchase #3	$189.70	6.601%	$202.2221	$202.22	$202.20	$202.20
Purchase #4	$163.27	12.851%	$184.2518	$184.25	$184.25	$184.30
Purchase #5	$234.60	6.683%	$250.2783	$250.28	$250.30	$250.30
Purchase #6	$53.46	13.328%	$60.5851	$60.59	$60.60	$60.60
Purchase #7	$142.59	11.273%	$158.6642	$158.66	$158.65	$158.70
7 purchase totals =	$1,015.15		$1,105.0415	$1,105.04	$1,105.05	$1,105.10