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	$173.54	13.227%	$196.4941	$196.49	$196.50	$196.50
Purchase #2	$138.97	4.811%	$145.6558	$145.66	$145.65	$145.70
Purchase #3	$172.83	3.751%	$179.3129	$179.31	$179.30	$179.30
Purchase #4	$27.60	13.507%	$31.3279	$31.33	$31.35	$31.30
Purchase #5	$179.86	11.420%	$200.4	$200.40	$200.40	$200.40
Purchase #6	$180.64	10.364%	$199.3615	$199.36	$199.35	$199.40
Purchase #7	$189.81	4.279%	$197.932	$197.93	$197.95	$197.90
7 purchase totals =	$1,063.25		$1,150.4842	$1,150.48	$1,150.50	$1,150.50