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	$162.38	10.111%	$178.7982	$178.80	$178.80	$178.80
Purchase #2	$112.96	11.194%	$125.6047	$125.60	$125.60	$125.60
Purchase #3	$187.40	4.501%	$195.8349	$195.83	$195.85	$195.80
Purchase #4	$52.86	9.570%	$57.9187	$57.92	$57.90	$57.90
Purchase #5	$208.74	11.705%	$233.173	$233.17	$233.15	$233.20
Purchase #6	$152.57	7.593%	$164.1546	$164.15	$164.15	$164.20
Purchase #7	$188.47	9.669%	$206.6932	$206.69	$206.70	$206.70
7 purchase totals =	$1,065.38		$1,162.1773	$1,162.16	$1,162.15	$1,162.20