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	$98.49	13.625%	$111.9093	$111.91	$111.90	$111.90
Purchase #2	$31.99	10.653%	$35.3979	$35.40	$35.40	$35.40
Purchase #3	$73.39	11.861%	$82.0948	$82.09	$82.10	$82.10
Purchase #4	$86.69	8.188%	$93.7882	$93.79	$93.80	$93.80
Purchase #5	$65.68	9.419%	$71.8664	$71.87	$71.85	$71.90
Purchase #6	$168.60	3.207%	$174.007	$174.01	$174.00	$174.00
Purchase #7	$156.68	5.275%	$164.9449	$164.94	$164.95	$164.90
7 purchase totals =	$681.52		$734.0085	$734.01	$734.00	$734.00