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	$169.28	7.351%	$181.7238	$181.72	$181.70	$181.70
Purchase #2	$79.29	7.863%	$85.5246	$85.52	$85.50	$85.50
Purchase #3	$9.74	8.681%	$10.5855	$10.59	$10.60	$10.60
Purchase #4	$23.86	8.434%	$25.8724	$25.87	$25.85	$25.90
Purchase #5	$239.32	7.212%	$256.5798	$256.58	$256.60	$256.60
Purchase #6	$157.78	3.245%	$162.9	$162.90	$162.90	$162.90
Purchase #7	$134.36	13.581%	$152.6074	$152.61	$152.60	$152.60
7 purchase totals =	$813.63		$875.7935	$875.79	$875.75	$875.80