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	$215.90	4.337%	$225.2636	$225.26	$225.25	$225.30
Purchase #2	$32.33	6.580%	$34.4573	$34.46	$34.45	$34.50
Purchase #3	$197.39	9.725%	$216.5862	$216.59	$216.60	$216.60
Purchase #4	$160.56	4.841%	$168.3327	$168.33	$168.35	$168.30
Purchase #5	$42.45	8.165%	$45.916	$45.92	$45.90	$45.90
Purchase #6	$179.61	3.385%	$185.6898	$185.69	$185.70	$185.70
Purchase #7	$194.51	12.780%	$219.3684	$219.37	$219.35	$219.40
7 purchase totals =	$1,022.75		$1,095.6140	$1,095.62	$1,095.60	$1,095.70