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	$172.95	7.142%	$185.3021	$185.30	$185.30	$185.30
Purchase #2	$214.73	12.540%	$241.6571	$241.66	$241.65	$241.70
Purchase #3	$9.85	10.541%	$10.8883	$10.89	$10.90	$10.90
Purchase #4	$160.72	6.327%	$170.8888	$170.89	$170.90	$170.90
Purchase #5	$84.85	6.636%	$90.4806	$90.48	$90.50	$90.50
Purchase #6	$221.44	7.817%	$238.75	$238.75	$238.75	$238.80
Purchase #7	$160.73	7.820%	$173.2991	$173.30	$173.30	$173.30
7 purchase totals =	$1,025.27		$1,111.2660	$1,111.27	$1,111.30	$1,111.40