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	$93.41	4.472%	$97.5873	$97.59	$97.60	$97.60
Purchase #2	$48.79	7.207%	$52.3063	$52.31	$52.30	$52.30
Purchase #3	$93.48	5.190%	$98.3316	$98.33	$98.35	$98.30
Purchase #4	$183.65	11.459%	$204.6945	$204.69	$204.70	$204.70
Purchase #5	$103.79	3.197%	$107.1082	$107.11	$107.10	$107.10
Purchase #6	$173.95	13.140%	$196.807	$196.81	$196.80	$196.80
Purchase #7	$234.70	10.628%	$259.6439	$259.64	$259.65	$259.60
7 purchase totals =	$931.77		$1,016.4788	$1,016.48	$1,016.50	$1,016.40