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	$153.58	7.253%	$164.7192	$164.72	$164.70	$164.70
Purchase #2	$92.69	7.652%	$99.7826	$99.78	$99.80	$99.80
Purchase #3	$82.50	10.346%	$91.0355	$91.04	$91.05	$91.00
Purchase #4	$189.97	10.333%	$209.5996	$209.60	$209.60	$209.60
Purchase #5	$167.49	4.457%	$174.955	$174.96	$174.95	$175.00
Purchase #6	$106.33	5.741%	$112.4344	$112.43	$112.45	$112.40
Purchase #7	$152.27	12.291%	$170.9855	$170.99	$171.00	$171.00
7 purchase totals =	$944.83		$1,023.5118	$1,023.52	$1,023.55	$1,023.50