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	$201.71	11.705%	$225.3202	$225.32	$225.30	$225.30
Purchase #2	$172.80	13.483%	$196.0986	$196.10	$196.10	$196.10
Purchase #3	$172.98	13.808%	$196.8651	$196.87	$196.85	$196.90
Purchase #4	$169.56	13.338%	$192.1759	$192.18	$192.20	$192.20
Purchase #5	$181.79	6.496%	$193.5991	$193.60	$193.60	$193.60
Purchase #6	$237.44	10.346%	$262.0055	$262.01	$262.00	$262.00
Purchase #7	$215.33	3.301%	$222.438	$222.44	$222.45	$222.40
7 purchase totals =	$1,351.61		$1,488.5024	$1,488.52	$1,488.50	$1,488.50