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	$208.74	4.205%	$217.5175	$217.52	$217.50	$217.50
Purchase #2	$53.91	4.556%	$56.3661	$56.37	$56.35	$56.40
Purchase #3	$88.80	3.747%	$92.1273	$92.13	$92.15	$92.10
Purchase #4	$158.59	13.170%	$179.4763	$179.48	$179.50	$179.50
Purchase #5	$137.64	11.740%	$153.7989	$153.80	$153.80	$153.80
Purchase #6	$199.64	11.278%	$222.1554	$222.16	$222.15	$222.20
Purchase #7	$178.50	6.352%	$189.8383	$189.84	$189.85	$189.80
7 purchase totals =	$1,025.82		$1,111.2798	$1,111.30	$1,111.30	$1,111.30