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	$58.95	6.821%	$62.971	$62.97	$62.95	$63.00
Purchase #2	$54.26	9.310%	$59.3116	$59.31	$59.30	$59.30
Purchase #3	$166.59	11.285%	$185.3897	$185.39	$185.40	$185.40
Purchase #4	$231.74	9.317%	$253.3312	$253.33	$253.35	$253.30
Purchase #5	$37.38	10.757%	$41.401	$41.40	$41.40	$41.40
Purchase #6	$204.85	6.852%	$218.8863	$218.89	$218.90	$218.90
Purchase #7	$243.65	3.363%	$251.8439	$251.84	$251.85	$251.80
7 purchase totals =	$997.42		$1,073.1347	$1,073.13	$1,073.15	$1,073.10