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	$187.56	4.503%	$196.0058	$196.01	$196.00	$196.00
Purchase #2	$145.27	13.125%	$164.3367	$164.34	$164.35	$164.30
Purchase #3	$124.29	13.799%	$141.4408	$141.44	$141.45	$141.40
Purchase #4	$250.33	3.842%	$259.9477	$259.95	$259.95	$259.90
Purchase #5	$56.32	10.606%	$62.2933	$62.29	$62.30	$62.30
Purchase #6	$160.69	11.380%	$178.9765	$178.98	$179.00	$179.00
Purchase #7	$89.38	4.637%	$93.5246	$93.52	$93.50	$93.50
7 purchase totals =	$1,013.84		$1,096.5254	$1,096.53	$1,096.55	$1,096.40