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	$35.74	6.173%	$37.9462	$37.95	$37.95	$37.90
Purchase #2	$149.39	11.697%	$166.8641	$166.86	$166.85	$166.90
Purchase #3	$210.46	5.451%	$221.9322	$221.93	$221.95	$221.90
Purchase #4	$179.67	6.841%	$191.9612	$191.96	$191.95	$192.00
Purchase #5	$133.72	6.293%	$142.135	$142.14	$142.15	$142.10
Purchase #6	$49.72	13.740%	$56.5515	$56.55	$56.55	$56.60
Purchase #7	$182.83	13.475%	$207.4663	$207.47	$207.45	$207.50
7 purchase totals =	$941.53		$1,024.8565	$1,024.86	$1,024.85	$1,024.90