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	$207.46	6.127%	$220.1711	$220.17	$220.15	$220.20
Purchase #2	$199.40	4.792%	$208.9552	$208.96	$208.95	$209.00
Purchase #3	$149.88	9.474%	$164.0796	$164.08	$164.10	$164.10
Purchase #4	$131.61	9.785%	$144.488	$144.49	$144.50	$144.50
Purchase #5	$113.98	11.435%	$127.0136	$127.01	$127.00	$127.00
Purchase #6	$6.90	12.343%	$7.7517	$7.75	$7.75	$7.80
Purchase #7	$184.76	6.324%	$196.4442	$196.44	$196.45	$196.40
7 purchase totals =	$993.99		$1,068.9034	$1,068.90	$1,068.90	$1,069.00