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	$119.65	5.260%	$125.9436	$125.94	$125.95	$125.90
Purchase #2	$219.66	7.499%	$236.1323	$236.13	$236.15	$236.10
Purchase #3	$168.77	7.166%	$180.8641	$180.86	$180.85	$180.90
Purchase #4	$142.36	9.311%	$155.6151	$155.62	$155.60	$155.60
Purchase #5	$84.88	5.833%	$89.8311	$89.83	$89.85	$89.80
Purchase #6	$197.53	7.371%	$212.0899	$212.09	$212.10	$212.10
Purchase #7	$103.48	5.656%	$109.3328	$109.33	$109.35	$109.30
7 purchase totals =	$1,036.33		$1,109.8089	$1,109.80	$1,109.85	$1,109.70