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	$43.51	5.640%	$45.964	$45.96	$45.95	$46.00
Purchase #2	$176.75	5.364%	$186.2309	$186.23	$186.25	$186.20
Purchase #3	$133.69	9.118%	$145.8799	$145.88	$145.90	$145.90
Purchase #4	$54.66	12.167%	$61.3105	$61.31	$61.30	$61.30
Purchase #5	$165.38	10.834%	$183.2973	$183.30	$183.30	$183.30
Purchase #6	$190.85	12.540%	$214.7826	$214.78	$214.80	$214.80
Purchase #7	$136.50	8.109%	$147.5688	$147.57	$147.55	$147.60
7 purchase totals =	$901.34		$985.0340	$985.03	$985.05	$985.10