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	$193.30	9.253%	$211.186	$211.19	$211.20	$211.20
Purchase #2	$22.28	6.454%	$23.718	$23.72	$23.70	$23.70
Purchase #3	$179.32	9.799%	$196.8916	$196.89	$196.90	$196.90
Purchase #4	$54.66	8.674%	$59.4012	$59.40	$59.40	$59.40
Purchase #5	$191.81	3.362%	$198.2587	$198.26	$198.25	$198.30
Purchase #6	$119.34	6.113%	$126.6353	$126.64	$126.65	$126.60
Purchase #7	$140.52	6.870%	$150.1737	$150.17	$150.15	$150.20
7 purchase totals =	$901.23		$966.2645	$966.27	$966.25	$966.30