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	$175.75	11.755%	$196.4094	$196.41	$196.40	$196.40
Purchase #2	$88.94	9.182%	$97.1065	$97.11	$97.10	$97.10
Purchase #3	$87.85	13.869%	$100.0339	$100.03	$100.05	$100.00
Purchase #4	$25.99	5.179%	$27.336	$27.34	$27.35	$27.30
Purchase #5	$183.56	11.640%	$204.9264	$204.93	$204.95	$204.90
Purchase #6	$58.50	5.200%	$61.542	$61.54	$61.55	$61.50
Purchase #7	$36.60	3.218%	$37.7778	$37.78	$37.80	$37.80
7 purchase totals =	$657.19		$725.1320	$725.14	$725.20	$725.00