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	$192.35	11.456%	$214.3856	$214.39	$214.40	$214.40
Purchase #2	$228.77	13.345%	$259.2994	$259.30	$259.30	$259.30
Purchase #3	$166.84	10.511%	$184.3766	$184.38	$184.40	$184.40
Purchase #4	$176.88	6.472%	$188.3277	$188.33	$188.35	$188.30
Purchase #5	$150.48	11.456%	$167.719	$167.72	$167.70	$167.70
Purchase #6	$34.41	7.609%	$37.0283	$37.03	$37.05	$37.00
Purchase #7	$31.79	11.466%	$35.435	$35.44	$35.45	$35.40
7 purchase totals =	$981.52		$1,086.5716	$1,086.59	$1,086.65	$1,086.50