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	$66.89	12.830%	$75.472	$75.47	$75.45	$75.50
Purchase #2	$85.72	13.451%	$97.2502	$97.25	$97.25	$97.30
Purchase #3	$139.52	9.236%	$152.4061	$152.41	$152.40	$152.40
Purchase #4	$156.35	9.281%	$170.8608	$170.86	$170.85	$170.90
Purchase #5	$178.80	9.619%	$195.9988	$196.00	$196.00	$196.00
Purchase #6	$211.73	13.497%	$240.3072	$240.31	$240.30	$240.30
Purchase #7	$234.89	11.585%	$262.102	$262.10	$262.10	$262.10
7 purchase totals =	$1,073.90		$1,194.3971	$1,194.40	$1,194.35	$1,194.50