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	$182.54	7.532%	$196.2889	$196.29	$196.30	$196.30
Purchase #2	$26.68	8.530%	$28.9558	$28.96	$28.95	$29.00
Purchase #3	$96.69	13.157%	$109.4115	$109.41	$109.40	$109.40
Purchase #4	$130.62	5.501%	$137.8054	$137.81	$137.80	$137.80
Purchase #5	$58.76	6.818%	$62.7663	$62.77	$62.75	$62.80
Purchase #6	$165.25	9.361%	$180.7191	$180.72	$180.70	$180.70
Purchase #7	$38.69	6.185%	$41.083	$41.08	$41.10	$41.10
7 purchase totals =	$699.23		$757.0300	$757.04	$757.00	$757.10