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	$58.53	5.857%	$61.9581	$61.96	$61.95	$62.00
Purchase #2	$106.85	10.656%	$118.2359	$118.24	$118.25	$118.20
Purchase #3	$224.53	8.151%	$242.8314	$242.83	$242.85	$242.80
Purchase #4	$215.86	9.645%	$236.6797	$236.68	$236.70	$236.70
Purchase #5	$159.66	7.173%	$171.1124	$171.11	$171.10	$171.10
Purchase #6	$130.54	5.336%	$137.5056	$137.51	$137.50	$137.50
Purchase #7	$175.85	3.571%	$182.1296	$182.13	$182.15	$182.10
7 purchase totals =	$1,071.82		$1,150.4527	$1,150.46	$1,150.50	$1,150.40