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	$125.30	13.664%	$142.421	$142.42	$142.40	$142.40
Purchase #2	$72.97	12.591%	$82.1577	$82.16	$82.15	$82.20
Purchase #3	$195.54	6.789%	$208.8152	$208.82	$208.80	$208.80
Purchase #4	$187.44	13.479%	$212.705	$212.71	$212.70	$212.70
Purchase #5	$172.96	8.243%	$187.2171	$187.22	$187.20	$187.20
Purchase #6	$40.92	10.445%	$45.1941	$45.19	$45.20	$45.20
Purchase #7	$198.41	4.682%	$207.6996	$207.70	$207.70	$207.70
7 purchase totals =	$993.54		$1,086.2097	$1,086.22	$1,086.15	$1,086.20