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	$98.53	5.846%	$104.2901	$104.29	$104.30	$104.30
Purchase #2	$55.88	10.774%	$61.9005	$61.90	$61.90	$61.90
Purchase #3	$196.41	6.212%	$208.611	$208.61	$208.60	$208.60
Purchase #4	$225.50	12.481%	$253.6447	$253.64	$253.65	$253.60
Purchase #5	$162.29	12.726%	$182.943	$182.94	$182.95	$182.90
Purchase #6	$80.80	5.493%	$85.2383	$85.24	$85.25	$85.20
Purchase #7	$186.45	12.700%	$210.1292	$210.13	$210.15	$210.10
7 purchase totals =	$1,005.86		$1,106.7568	$1,106.75	$1,106.80	$1,106.60