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	$175.58	7.674%	$189.054	$189.05	$189.05	$189.10
Purchase #2	$47.86	9.731%	$52.5173	$52.52	$52.50	$52.50
Purchase #3	$74.49	10.605%	$82.3897	$82.39	$82.40	$82.40
Purchase #4	$148.91	12.445%	$167.4418	$167.44	$167.45	$167.40
Purchase #5	$175.34	8.599%	$190.4175	$190.42	$190.40	$190.40
Purchase #6	$208.30	6.818%	$222.5019	$222.50	$222.50	$222.50
Purchase #7	$152.98	7.216%	$164.019	$164.02	$164.00	$164.00
7 purchase totals =	$983.46		$1,068.3412	$1,068.34	$1,068.30	$1,068.30