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	$192.74	4.104%	$200.65	$200.65	$200.65	$200.70
Purchase #2	$69.77	3.457%	$72.1819	$72.18	$72.20	$72.20
Purchase #3	$72.70	13.127%	$82.2433	$82.24	$82.25	$82.20
Purchase #4	$5.33	11.330%	$5.9339	$5.93	$5.95	$5.90
Purchase #5	$133.83	11.752%	$149.5577	$149.56	$149.55	$149.60
Purchase #6	$41.51	13.647%	$47.1749	$47.17	$47.15	$47.20
Purchase #7	$168.50	9.404%	$184.3457	$184.35	$184.35	$184.30
7 purchase totals =	$684.38		$742.0874	$742.08	$742.10	$742.10