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	$212.91	5.566%	$224.7606	$224.76	$224.75	$224.80
Purchase #2	$78.96	11.868%	$88.331	$88.33	$88.35	$88.30
Purchase #3	$244.36	3.744%	$253.5088	$253.51	$253.50	$253.50
Purchase #4	$151.32	3.682%	$156.8916	$156.89	$156.90	$156.90
Purchase #5	$132.91	13.773%	$151.2157	$151.22	$151.20	$151.20
Purchase #6	$60.40	6.807%	$64.5114	$64.51	$64.50	$64.50
Purchase #7	$141.98	9.738%	$155.806	$155.81	$155.80	$155.80
7 purchase totals =	$1,022.84		$1,095.0251	$1,095.03	$1,095.00	$1,095.00