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	$125.85	4.592%	$131.629	$131.63	$131.65	$131.60
Purchase #2	$18.28	3.802%	$18.975	$18.98	$19.00	$19.00
Purchase #3	$54.67	5.323%	$57.5801	$57.58	$57.60	$57.60
Purchase #4	$153.51	7.486%	$165.0018	$165.00	$165.00	$165.00
Purchase #5	$93.66	6.221%	$99.4866	$99.49	$99.50	$99.50
Purchase #6	$190.76	4.111%	$198.6021	$198.60	$198.60	$198.60
Purchase #7	$151.31	5.636%	$159.8378	$159.84	$159.85	$159.80
7 purchase totals =	$788.04		$831.1124	$831.12	$831.20	$831.10