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	$93.29	13.819%	$106.1817	$106.18	$106.20	$106.20
Purchase #2	$199.66	5.274%	$210.1901	$210.19	$210.20	$210.20
Purchase #3	$230.40	5.856%	$243.8922	$243.89	$243.90	$243.90
Purchase #4	$170.56	8.226%	$184.5903	$184.59	$184.60	$184.60
Purchase #5	$6.73	9.859%	$7.3935	$7.39	$7.40	$7.40
Purchase #6	$158.52	6.435%	$168.7208	$168.72	$168.70	$168.70
Purchase #7	$145.83	13.550%	$165.59	$165.59	$165.60	$165.60
7 purchase totals =	$1,004.99		$1,086.5586	$1,086.55	$1,086.60	$1,086.60