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	$35.53	4.342%	$37.0727	$37.07	$37.05	$37.10
Purchase #2	$59.81	12.153%	$67.0787	$67.08	$67.10	$67.10
Purchase #3	$210.67	9.548%	$230.7848	$230.78	$230.80	$230.80
Purchase #4	$154.54	9.153%	$168.685	$168.69	$168.70	$168.70
Purchase #5	$151.90	6.517%	$161.7993	$161.80	$161.80	$161.80
Purchase #6	$138.57	5.629%	$146.3701	$146.37	$146.35	$146.40
Purchase #7	$219.77	13.831%	$250.1664	$250.17	$250.15	$250.20
7 purchase totals =	$970.79		$1,061.9570	$1,061.96	$1,061.95	$1,062.10