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	$152.57	5.854%	$161.5014	$161.50	$161.50	$161.50
Purchase #2	$169.64	5.192%	$178.4477	$178.45	$178.45	$178.40
Purchase #3	$31.83	6.408%	$33.8697	$33.87	$33.85	$33.90
Purchase #4	$153.36	4.616%	$160.4391	$160.44	$160.45	$160.40
Purchase #5	$60.52	7.631%	$65.1383	$65.14	$65.15	$65.10
Purchase #6	$218.54	7.752%	$235.4812	$235.48	$235.50	$235.50
Purchase #7	$211.41	5.196%	$222.3949	$222.39	$222.40	$222.40
7 purchase totals =	$997.87		$1,057.2723	$1,057.27	$1,057.30	$1,057.20