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	$211.65	7.682%	$227.909	$227.91	$227.90	$227.90
Purchase #2	$165.82	11.685%	$185.1961	$185.20	$185.20	$185.20
Purchase #3	$57.93	3.121%	$59.738	$59.74	$59.75	$59.70
Purchase #4	$152.69	10.655%	$168.9591	$168.96	$168.95	$169.00
Purchase #5	$241.56	13.836%	$274.9822	$274.98	$275.00	$275.00
Purchase #6	$93.82	12.297%	$105.357	$105.36	$105.35	$105.40
Purchase #7	$6.59	3.141%	$6.797	$6.80	$6.80	$6.80
7 purchase totals =	$930.06		$1,028.9384	$1,028.95	$1,028.95	$1,029.00