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	$57.77	7.110%	$61.8774	$61.88	$61.90	$61.90
Purchase #2	$76.79	6.478%	$81.7645	$81.76	$81.75	$81.80
Purchase #3	$81.97	5.832%	$86.7505	$86.75	$86.75	$86.80
Purchase #4	$168.66	9.783%	$185.16	$185.16	$185.15	$185.20
Purchase #5	$158.36	4.601%	$165.6461	$165.65	$165.65	$165.60
Purchase #6	$35.63	5.285%	$37.513	$37.51	$37.50	$37.50
Purchase #7	$136.65	4.276%	$142.4932	$142.49	$142.50	$142.50
7 purchase totals =	$715.83		$761.2047	$761.20	$761.20	$761.30