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	$175.72	10.292%	$193.8051	$193.81	$193.80	$193.80
Purchase #2	$58.48	12.872%	$66.0075	$66.01	$66.00	$66.00
Purchase #3	$86.95	7.327%	$93.3208	$93.32	$93.30	$93.30
Purchase #4	$234.63	11.501%	$261.6148	$261.61	$261.60	$261.60
Purchase #5	$188.89	11.224%	$210.091	$210.09	$210.10	$210.10
Purchase #6	$232.89	10.133%	$256.4887	$256.49	$256.50	$256.50
Purchase #7	$85.51	6.377%	$90.963	$90.96	$90.95	$91.00
7 purchase totals =	$1,063.07		$1,172.2909	$1,172.29	$1,172.25	$1,172.30