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	$162.41	11.705%	$181.4201	$181.42	$181.40	$181.40
Purchase #2	$172.89	6.508%	$184.1417	$184.14	$184.15	$184.10
Purchase #3	$42.53	13.585%	$48.3077	$48.31	$48.30	$48.30
Purchase #4	$10.43	10.690%	$11.545	$11.55	$11.55	$11.50
Purchase #5	$246.28	7.435%	$264.5909	$264.59	$264.60	$264.60
Purchase #6	$137.54	13.812%	$156.537	$156.54	$156.55	$156.50
Purchase #7	$186.36	11.650%	$208.0709	$208.07	$208.05	$208.10
7 purchase totals =	$958.44		$1,054.6133	$1,054.62	$1,054.60	$1,054.50