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	$40.68	11.482%	$45.3509	$45.35	$45.35	$45.40
Purchase #2	$106.46	8.684%	$115.705	$115.71	$115.70	$115.70
Purchase #3	$214.31	6.639%	$228.538	$228.54	$228.55	$228.50
Purchase #4	$124.42	7.272%	$133.4678	$133.47	$133.45	$133.50
Purchase #5	$101.81	9.203%	$111.1796	$111.18	$111.20	$111.20
Purchase #6	$217.80	9.428%	$238.3342	$238.33	$238.35	$238.30
Purchase #7	$219.91	8.820%	$239.3061	$239.31	$239.30	$239.30
7 purchase totals =	$1,025.39		$1,111.8816	$1,111.89	$1,111.90	$1,111.90