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	$204.62	8.822%	$222.6716	$222.67	$222.65	$222.70
Purchase #2	$136.35	4.439%	$142.4026	$142.40	$142.40	$142.40
Purchase #3	$190.29	11.313%	$211.8175	$211.82	$211.80	$211.80
Purchase #4	$84.33	13.584%	$95.7854	$95.79	$95.80	$95.80
Purchase #5	$89.95	7.711%	$96.886	$96.89	$96.90	$96.90
Purchase #6	$244.67	3.871%	$254.1412	$254.14	$254.15	$254.10
Purchase #7	$150.95	7.102%	$161.6705	$161.67	$161.65	$161.70
7 purchase totals =	$1,101.16		$1,185.3748	$1,185.38	$1,185.35	$1,185.40