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	$192.34	6.805%	$205.4287	$205.43	$205.45	$205.40
Purchase #2	$196.57	11.291%	$218.7647	$218.76	$218.75	$218.80
Purchase #3	$225.54	10.340%	$248.8608	$248.86	$248.85	$248.90
Purchase #4	$105.94	3.802%	$109.9678	$109.97	$109.95	$110.00
Purchase #5	$193.50	13.191%	$219.0246	$219.02	$219.00	$219.00
Purchase #6	$169.68	12.780%	$191.3651	$191.37	$191.35	$191.40
Purchase #7	$196.30	11.265%	$218.4132	$218.41	$218.40	$218.40
7 purchase totals =	$1,279.87		$1,411.8249	$1,411.82	$1,411.75	$1,411.90