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	$104.31	7.116%	$111.7327	$111.73	$111.75	$111.70
Purchase #2	$174.96	7.179%	$187.5204	$187.52	$187.50	$187.50
Purchase #3	$66.99	5.402%	$70.6088	$70.61	$70.60	$70.60
Purchase #4	$170.95	5.186%	$179.8155	$179.82	$179.80	$179.80
Purchase #5	$56.72	3.217%	$58.5447	$58.54	$58.55	$58.50
Purchase #6	$131.58	7.528%	$141.4853	$141.49	$141.50	$141.50
Purchase #7	$191.27	7.842%	$206.2694	$206.27	$206.25	$206.30
7 purchase totals =	$896.78		$955.9768	$955.98	$955.95	$955.90