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	$150.29	11.145%	$167.0398	$167.04	$167.05	$167.00
Purchase #2	$155.53	9.235%	$169.8932	$169.89	$169.90	$169.90
Purchase #3	$227.70	10.156%	$250.8252	$250.83	$250.85	$250.80
Purchase #4	$170.63	12.514%	$191.9826	$191.98	$192.00	$192.00
Purchase #5	$85.97	6.871%	$91.877	$91.88	$91.90	$91.90
Purchase #6	$86.78	13.694%	$98.6637	$98.66	$98.65	$98.70
Purchase #7	$50.81	9.689%	$55.733	$55.73	$55.75	$55.70
7 purchase totals =	$927.71		$1,026.0145	$1,026.01	$1,026.10	$1,026.00