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	$196.50	13.218%	$222.4734	$222.47	$222.45	$222.50
Purchase #2	$118.97	4.484%	$124.3046	$124.30	$124.30	$124.30
Purchase #3	$38.37	13.373%	$43.5012	$43.50	$43.50	$43.50
Purchase #4	$135.42	5.255%	$142.5363	$142.54	$142.55	$142.50
Purchase #5	$232.46	5.633%	$245.5545	$245.55	$245.55	$245.60
Purchase #6	$99.96	13.157%	$113.1117	$113.11	$113.10	$113.10
Purchase #7	$132.79	4.459%	$138.7111	$138.71	$138.70	$138.70
7 purchase totals =	$954.47		$1,030.1928	$1,030.18	$1,030.15	$1,030.20