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	$169.48	12.451%	$190.582	$190.58	$190.60	$190.60
Purchase #2	$33.99	9.612%	$37.2571	$37.26	$37.25	$37.30
Purchase #3	$147.93	5.618%	$156.2407	$156.24	$156.25	$156.20
Purchase #4	$234.86	13.755%	$267.165	$267.17	$267.15	$267.20
Purchase #5	$52.88	9.138%	$57.7122	$57.71	$57.70	$57.70
Purchase #6	$120.31	9.458%	$131.6889	$131.69	$131.70	$131.70
Purchase #7	$154.85	11.304%	$172.3542	$172.35	$172.35	$172.40
7 purchase totals =	$914.30		$1,013.0001	$1,013.00	$1,013.00	$1,013.10