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	$155.91	10.735%	$172.6469	$172.65	$172.65	$172.60
Purchase #2	$38.67	12.719%	$43.5884	$43.59	$43.60	$43.60
Purchase #3	$141.54	11.342%	$157.5935	$157.59	$157.60	$157.60
Purchase #4	$245.31	9.446%	$268.482	$268.48	$268.50	$268.50
Purchase #5	$73.68	3.374%	$76.166	$76.17	$76.15	$76.20
Purchase #6	$213.85	10.540%	$236.3898	$236.39	$236.40	$236.40
Purchase #7	$89.89	12.499%	$101.1254	$101.13	$101.15	$101.10
7 purchase totals =	$958.85		$1,055.9920	$1,056.00	$1,056.05	$1,056.00