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	$175.89	11.607%	$196.3056	$196.31	$196.30	$196.30
Purchase #2	$102.34	8.666%	$111.2088	$111.21	$111.20	$111.20
Purchase #3	$154.35	7.506%	$165.9355	$165.94	$165.95	$165.90
Purchase #4	$180.65	11.184%	$200.8539	$200.85	$200.85	$200.90
Purchase #5	$232.58	6.784%	$248.3582	$248.36	$248.35	$248.40
Purchase #6	$28.38	12.157%	$31.8302	$31.83	$31.85	$31.80
Purchase #7	$89.45	4.628%	$93.5897	$93.59	$93.60	$93.60
7 purchase totals =	$963.64		$1,048.0819	$1,048.09	$1,048.10	$1,048.10