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	$157.58	4.149%	$164.118	$164.12	$164.10	$164.10
Purchase #2	$80.56	6.548%	$85.8351	$85.84	$85.85	$85.80
Purchase #3	$243.35	12.148%	$272.9122	$272.91	$272.90	$272.90
Purchase #4	$67.46	5.347%	$71.0671	$71.07	$71.05	$71.10
Purchase #5	$124.33	11.842%	$139.0532	$139.05	$139.05	$139.10
Purchase #6	$151.57	4.703%	$158.6983	$158.70	$158.70	$158.70
Purchase #7	$149.88	13.671%	$170.3701	$170.37	$170.35	$170.40
7 purchase totals =	$974.73		$1,062.0540	$1,062.06	$1,062.00	$1,062.10