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	$208.73	11.165%	$232.0347	$232.03	$232.05	$232.00
Purchase #2	$82.86	8.219%	$89.6703	$89.67	$89.65	$89.70
Purchase #3	$95.65	6.749%	$102.1054	$102.11	$102.10	$102.10
Purchase #4	$74.82	4.764%	$78.3844	$78.38	$78.40	$78.40
Purchase #5	$123.59	10.505%	$136.5731	$136.57	$136.55	$136.60
Purchase #6	$7.28	4.125%	$7.5803	$7.58	$7.60	$7.60
Purchase #7	$65.59	9.276%	$71.6741	$71.67	$71.65	$71.70
7 purchase totals =	$658.52		$718.0223	$718.01	$718.00	$718.10