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	$88.26	4.616%	$92.3341	$92.33	$92.35	$92.30
Purchase #2	$55.34	8.236%	$59.8978	$59.90	$59.90	$59.90
Purchase #3	$192.47	12.205%	$215.961	$215.96	$215.95	$216.00
Purchase #4	$180.53	5.123%	$189.7786	$189.78	$189.80	$189.80
Purchase #5	$66.85	4.556%	$69.8957	$69.90	$69.90	$69.90
Purchase #6	$230.82	3.434%	$238.7464	$238.75	$238.75	$238.70
Purchase #7	$216.74	6.420%	$230.6547	$230.65	$230.65	$230.70
7 purchase totals =	$1,031.01		$1,097.2683	$1,097.27	$1,097.30	$1,097.30