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	$164.94	4.267%	$171.978	$171.98	$172.00	$172.00
Purchase #2	$82.36	13.130%	$93.1739	$93.17	$93.15	$93.20
Purchase #3	$172.85	11.248%	$192.2922	$192.29	$192.30	$192.30
Purchase #4	$78.71	8.128%	$85.1075	$85.11	$85.10	$85.10
Purchase #5	$153.76	11.453%	$171.3701	$171.37	$171.35	$171.40
Purchase #6	$105.53	8.760%	$114.7744	$114.77	$114.75	$114.80
Purchase #7	$220.27	11.767%	$246.1892	$246.19	$246.20	$246.20
7 purchase totals =	$978.42		$1,074.8853	$1,074.88	$1,074.85	$1,075.00