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	$169.82	12.151%	$190.4548	$190.45	$190.45	$190.50
Purchase #2	$67.50	11.789%	$75.4576	$75.46	$75.45	$75.50
Purchase #3	$164.42	5.842%	$174.0254	$174.03	$174.05	$174.00
Purchase #4	$167.89	10.589%	$185.6679	$185.67	$185.65	$185.70
Purchase #5	$189.73	3.317%	$196.0233	$196.02	$196.00	$196.00
Purchase #6	$66.43	10.367%	$73.3168	$73.32	$73.30	$73.30
Purchase #7	$151.73	9.145%	$165.6057	$165.61	$165.60	$165.60
7 purchase totals =	$977.52		$1,060.5515	$1,060.56	$1,060.50	$1,060.60