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	$94.37	11.299%	$105.0329	$105.03	$105.05	$105.00
Purchase #2	$164.61	12.400%	$185.0216	$185.02	$185.00	$185.00
Purchase #3	$37.96	7.526%	$40.8169	$40.82	$40.80	$40.80
Purchase #4	$99.92	9.214%	$109.1266	$109.13	$109.15	$109.10
Purchase #5	$203.76	4.138%	$212.1916	$212.19	$212.20	$212.20
Purchase #6	$143.73	13.421%	$163.02	$163.02	$163.00	$163.00
Purchase #7	$188.96	11.190%	$210.1046	$210.10	$210.10	$210.10
7 purchase totals =	$933.31		$1,025.3142	$1,025.31	$1,025.30	$1,025.20