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	$205.98	10.640%	$227.8963	$227.90	$227.90	$227.90
Purchase #2	$166.46	4.517%	$173.979	$173.98	$174.00	$174.00
Purchase #3	$247.92	5.240%	$260.911	$260.91	$260.90	$260.90
Purchase #4	$61.48	5.757%	$65.0194	$65.02	$65.00	$65.00
Purchase #5	$209.29	11.527%	$233.4149	$233.41	$233.40	$233.40
Purchase #6	$31.27	11.280%	$34.7973	$34.80	$34.80	$34.80
Purchase #7	$31.39	3.820%	$32.5891	$32.59	$32.60	$32.60
7 purchase totals =	$953.79		$1,028.6070	$1,028.61	$1,028.60	$1,028.60