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	$190.25	3.488%	$196.8859	$196.89	$196.90	$196.90
Purchase #2	$76.46	11.871%	$85.5366	$85.54	$85.55	$85.50
Purchase #3	$162.81	12.853%	$183.736	$183.74	$183.75	$183.70
Purchase #4	$245.83	10.803%	$272.387	$272.39	$272.40	$272.40
Purchase #5	$31.52	5.239%	$33.1713	$33.17	$33.15	$33.20
Purchase #6	$179.98	4.577%	$188.2177	$188.22	$188.20	$188.20
Purchase #7	$173.44	9.146%	$189.3028	$189.30	$189.30	$189.30
7 purchase totals =	$1,060.29		$1,149.2373	$1,149.25	$1,149.25	$1,149.20