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	$188.86	7.614%	$203.2398	$203.24	$203.25	$203.20
Purchase #2	$173.50	13.346%	$196.6553	$196.66	$196.65	$196.70
Purchase #3	$42.88	12.128%	$48.0805	$48.08	$48.10	$48.10
Purchase #4	$96.69	7.645%	$104.082	$104.08	$104.10	$104.10
Purchase #5	$203.79	7.742%	$219.5674	$219.57	$219.55	$219.60
Purchase #6	$241.69	3.551%	$250.2724	$250.27	$250.25	$250.30
Purchase #7	$143.94	11.797%	$160.9206	$160.92	$160.90	$160.90
7 purchase totals =	$1,091.35		$1,182.8180	$1,182.82	$1,182.80	$1,182.90