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	$41.99	3.186%	$43.3278	$43.33	$43.35	$43.30
Purchase #2	$6.37	12.339%	$7.156	$7.16	$7.15	$7.20
Purchase #3	$93.35	3.711%	$96.8142	$96.81	$96.80	$96.80
Purchase #4	$196.57	13.647%	$223.3959	$223.40	$223.40	$223.40
Purchase #5	$202.75	13.105%	$229.3204	$229.32	$229.30	$229.30
Purchase #6	$141.46	10.386%	$156.152	$156.15	$156.15	$156.20
Purchase #7	$222.87	10.284%	$245.79	$245.79	$245.80	$245.80
7 purchase totals =	$905.36		$1,001.9563	$1,001.96	$1,001.95	$1,002.00