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	$92.56	10.334%	$102.1252	$102.13	$102.15	$102.10
Purchase #2	$174.41	5.231%	$183.5334	$183.53	$183.55	$183.50
Purchase #3	$245.55	4.444%	$256.4622	$256.46	$256.45	$256.50
Purchase #4	$210.43	5.870%	$222.7822	$222.78	$222.80	$222.80
Purchase #5	$165.61	8.198%	$179.1867	$179.19	$179.20	$179.20
Purchase #6	$104.91	4.592%	$109.7275	$109.73	$109.75	$109.70
Purchase #7	$31.75	3.684%	$32.9197	$32.92	$32.90	$32.90
7 purchase totals =	$1,025.22		$1,086.7369	$1,086.74	$1,086.80	$1,086.70