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	$213.48	7.384%	$229.2434	$229.24	$229.25	$229.20
Purchase #2	$127.69	3.650%	$132.3507	$132.35	$132.35	$132.40
Purchase #3	$156.75	9.405%	$171.4923	$171.49	$171.50	$171.50
Purchase #4	$122.82	6.618%	$130.9482	$130.95	$130.95	$130.90
Purchase #5	$203.54	11.418%	$226.7802	$226.78	$226.80	$226.80
Purchase #6	$127.85	3.484%	$132.3043	$132.30	$132.30	$132.30
Purchase #7	$64.34	12.593%	$72.4423	$72.44	$72.45	$72.40
7 purchase totals =	$1,016.47		$1,095.5614	$1,095.55	$1,095.60	$1,095.50