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	$43.70	7.431%	$46.9473	$46.95	$46.95	$46.90
Purchase #2	$38.54	7.242%	$41.3311	$41.33	$41.35	$41.30
Purchase #3	$188.41	8.799%	$204.9882	$204.99	$205.00	$205.00
Purchase #4	$153.28	9.572%	$167.952	$167.95	$167.95	$168.00
Purchase #5	$196.48	12.631%	$221.2974	$221.30	$221.30	$221.30
Purchase #6	$102.49	13.494%	$116.32	$116.32	$116.30	$116.30
Purchase #7	$52.33	13.694%	$59.4961	$59.50	$59.50	$59.50
7 purchase totals =	$775.23		$858.3321	$858.34	$858.35	$858.30