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	$176.62	13.437%	$200.3524	$200.35	$200.35	$200.40
Purchase #2	$178.53	6.459%	$190.0613	$190.06	$190.05	$190.10
Purchase #3	$47.67	11.285%	$53.0496	$53.05	$53.05	$53.00
Purchase #4	$129.25	6.309%	$137.4044	$137.40	$137.40	$137.40
Purchase #5	$67.54	11.384%	$75.2288	$75.23	$75.25	$75.20
Purchase #6	$139.90	5.345%	$147.3777	$147.38	$147.40	$147.40
Purchase #7	$222.66	12.669%	$250.8688	$250.87	$250.85	$250.90
7 purchase totals =	$962.17		$1,054.3430	$1,054.34	$1,054.35	$1,054.40