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	$87.53	9.838%	$96.1412	$96.14	$96.15	$96.10
Purchase #2	$79.28	4.609%	$82.934	$82.93	$82.95	$82.90
Purchase #3	$203.34	11.379%	$226.4781	$226.48	$226.50	$226.50
Purchase #4	$205.86	13.419%	$233.4844	$233.48	$233.50	$233.50
Purchase #5	$127.79	6.683%	$136.3302	$136.33	$136.35	$136.30
Purchase #6	$176.56	7.539%	$189.8709	$189.87	$189.85	$189.90
Purchase #7	$142.91	6.870%	$152.7279	$152.73	$152.75	$152.70
7 purchase totals =	$1,023.27		$1,117.9667	$1,117.96	$1,118.05	$1,117.90