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	$44.25	3.818%	$45.9395	$45.94	$45.95	$45.90
Purchase #2	$96.90	9.324%	$105.935	$105.94	$105.95	$105.90
Purchase #3	$169.61	7.860%	$182.9413	$182.94	$182.95	$182.90
Purchase #4	$59.63	9.819%	$65.4851	$65.49	$65.50	$65.50
Purchase #5	$157.75	5.179%	$165.9199	$165.92	$165.90	$165.90
Purchase #6	$190.35	12.447%	$214.0429	$214.04	$214.05	$214.00
Purchase #7	$61.35	10.351%	$67.7003	$67.70	$67.70	$67.70
7 purchase totals =	$779.84		$847.9640	$847.97	$848.00	$847.80