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	$162.75	7.515%	$174.9807	$174.98	$175.00	$175.00
Purchase #2	$145.46	13.346%	$164.8731	$164.87	$164.85	$164.90
Purchase #3	$61.36	8.733%	$66.7186	$66.72	$66.70	$66.70
Purchase #4	$151.58	12.835%	$171.0353	$171.04	$171.05	$171.00
Purchase #5	$165.78	5.872%	$175.5146	$175.51	$175.50	$175.50
Purchase #6	$50.87	6.741%	$54.2991	$54.30	$54.30	$54.30
Purchase #7	$192.87	10.107%	$212.3634	$212.36	$212.35	$212.40
7 purchase totals =	$930.67		$1,019.7848	$1,019.78	$1,019.75	$1,019.80