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	$118.51	4.265%	$123.5645	$123.56	$123.55	$123.60
Purchase #2	$246.99	7.301%	$265.0227	$265.02	$265.00	$265.00
Purchase #3	$172.61	5.272%	$181.71	$181.71	$181.70	$181.70
Purchase #4	$168.88	11.672%	$188.5917	$188.59	$188.60	$188.60
Purchase #5	$179.50	12.110%	$201.2375	$201.24	$201.25	$201.20
Purchase #6	$143.94	12.730%	$162.2636	$162.26	$162.25	$162.30
Purchase #7	$31.98	12.217%	$35.887	$35.89	$35.90	$35.90
7 purchase totals =	$1,062.41		$1,158.2770	$1,158.27	$1,158.25	$1,158.30