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	$107.57	4.488%	$112.3977	$112.40	$112.40	$112.40
Purchase #2	$102.25	11.637%	$114.1488	$114.15	$114.15	$114.10
Purchase #3	$232.75	3.461%	$240.8055	$240.81	$240.80	$240.80
Purchase #4	$147.31	3.198%	$152.021	$152.02	$152.00	$152.00
Purchase #5	$209.42	13.235%	$237.1367	$237.14	$237.15	$237.10
Purchase #6	$156.63	9.506%	$171.5192	$171.52	$171.50	$171.50
Purchase #7	$94.48	11.637%	$105.4746	$105.47	$105.45	$105.50
7 purchase totals =	$1,050.41		$1,133.5035	$1,133.51	$1,133.45	$1,133.40