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	$126.27	11.690%	$141.031	$141.03	$141.05	$141.00
Purchase #2	$180.40	6.802%	$192.6708	$192.67	$192.65	$192.70
Purchase #3	$109.38	9.661%	$119.9472	$119.95	$119.95	$119.90
Purchase #4	$172.52	8.114%	$186.5183	$186.52	$186.50	$186.50
Purchase #5	$248.61	11.659%	$277.5954	$277.60	$277.60	$277.60
Purchase #6	$68.71	4.769%	$71.9868	$71.99	$72.00	$72.00
Purchase #7	$179.27	9.695%	$196.6502	$196.65	$196.65	$196.70
7 purchase totals =	$1,085.16		$1,186.3997	$1,186.41	$1,186.40	$1,186.40