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	$134.36	5.302%	$141.4838	$141.48	$141.50	$141.50
Purchase #2	$232.32	13.592%	$263.8969	$263.90	$263.90	$263.90
Purchase #3	$40.30	7.503%	$43.3237	$43.32	$43.30	$43.30
Purchase #4	$215.71	5.300%	$227.1426	$227.14	$227.15	$227.10
Purchase #5	$52.42	8.778%	$57.0214	$57.02	$57.00	$57.00
Purchase #6	$237.85	13.836%	$270.7589	$270.76	$270.75	$270.80
Purchase #7	$83.37	13.137%	$94.3223	$94.32	$94.30	$94.30
7 purchase totals =	$996.33		$1,097.9496	$1,097.94	$1,097.90	$1,097.90