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	$78.93	8.745%	$85.8324	$85.83	$85.85	$85.80
Purchase #2	$40.61	6.727%	$43.3418	$43.34	$43.35	$43.30
Purchase #3	$248.46	13.386%	$281.7189	$281.72	$281.70	$281.70
Purchase #4	$69.33	5.798%	$73.3498	$73.35	$73.35	$73.30
Purchase #5	$152.44	13.377%	$172.8319	$172.83	$172.85	$172.80
Purchase #6	$222.76	5.443%	$234.8848	$234.88	$234.90	$234.90
Purchase #7	$169.54	13.632%	$192.6517	$192.65	$192.65	$192.70
7 purchase totals =	$982.07		$1,084.6113	$1,084.60	$1,084.65	$1,084.50