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	$176.73	11.399%	$196.8755	$196.88	$196.90	$196.90
Purchase #2	$133.51	11.529%	$148.9024	$148.90	$148.90	$148.90
Purchase #3	$129.85	9.515%	$142.2052	$142.21	$142.20	$142.20
Purchase #4	$39.54	11.312%	$44.0128	$44.01	$44.00	$44.00
Purchase #5	$244.73	9.617%	$268.2657	$268.27	$268.25	$268.30
Purchase #6	$138.65	6.420%	$147.5513	$147.55	$147.55	$147.60
Purchase #7	$53.76	10.547%	$59.4301	$59.43	$59.45	$59.40
7 purchase totals =	$916.77		$1,007.2430	$1,007.25	$1,007.25	$1,007.30